Douglas Martin - Academia.edu (original) (raw)

Papers by Douglas Martin

The Southwestern Naturalist, 2014

ABSTRACT The variable platyfish (Xiphophorus variatus), native to Gulf Coast drainages of norther... more ABSTRACT The variable platyfish (Xiphophorus variatus), native to Gulf Coast drainages of northern Mexico, is a popular aquarium fish with a long history of introduction globally. We document the first Texas occurrence of this species, and its persistence in highly urban Waller Creek in the city of Austin since at least 2004. The population appears to be limited to Waller Creek, having not yet been found in neighboring creeks where similar habitat exists. We observed individuals in situ and in the lab surviving in 7°C water, well below published thermal minima, and report its persistence through one of the coldest winters in Austin's recorded history. Its persistence may be due to a combination of its cold tolerance and the presence of thermal refuges. In the lab we found that individuals purchased in a local pet store and individuals from Waller Creek had the same cold tolerance.

Hydrobiologia, 2008

We report the results of a 3-year study of ichthyoplankton in the lower Savannah River and its co... more We report the results of a 3-year study of ichthyoplankton in the lower Savannah River and its coastal plain tributaries. Sampling was weekly from February through July in 1983, 1984 and 1985. Ichthyoplankton transport was used as an estimate of ichthyoplankton production. Ichthyoplankton transport in the river, for both total and most common taxa, was highest in 1983 and lowest

1999 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (Cat. No.99TH8399), 1999

Abstract Four servo loop designs for disk drive dual-stage actuatqr ,systems are studied. The cha... more Abstract Four servo loop designs for disk drive dual-stage actuatqr ,systems are studied. The characteristics and benefits of-each design are Giscussed. A parallel loop structure has been designed for a dual loop system with suspension based piezoelectric micro-actuators. ...

American journal of cardiovascular disease, 2015

Alteration of ubiquitin-proteasome system (UPS) mediated protein degradation has been implicated ... more Alteration of ubiquitin-proteasome system (UPS) mediated protein degradation has been implicated in the progression from a large subset of heart disease to congestive heart failure, rendering it extremely important to elucidate the cellular and molecular mechanism by which the UPS is regulated. Cullin-RING ligases (CRLs) represent the largest family of ubiquitin ligases crucial for UPS-dependent proteolysis. Serving as a cullin deneddylase, the COP9 signalosome (CSN) regulates the activity and assembly of CRLs. In the past several years, emerging studies have begun to unveil the role of the CSN and some of the CRLs in cardiomyocytes or the heart under physiological and pathological conditions. This review article will highlight and analyze these recent progresses and provide the author's perspective on the future directions for this research field.

American journal of cardiovascular disease, 2015

Disorders of vascular function contribute importantly to cardiovascular disease which represents ... more Disorders of vascular function contribute importantly to cardiovascular disease which represents a substantial cause of morbidity and mortality worldwide. An emerging paradigm in the study of cardiovascular diseases is that protein ubiquitination and turnover represent key pathological mechanisms. Our understanding of these processes in the vasculature is growing but remains incomplete. Since protein ubiquitination and turnover can represent a terminal event in the life of a given protein, entry into these pathways must be highly regulated. However, at present understanding of these regulatory mechanisms, particularly in the vasculature, is fragmentary. The COP9 (constitutive photomorphogenic mutant 9) signalosome (CSN) is a heteromeric protein complex implicated in the control of protein degradation. The CSN participates critically in the control of Cullin Ring Ligases (CRLs), at least in part via the detachment of a small protein, Nedd8 (deneddylation). CRLs are one of the largest...

Gynecologic oncology, Jan 29, 2015

Every year almost 95,000 women are diagnosed with a gynecologic malignancy and over 28,000 women ... more Every year almost 95,000 women are diagnosed with a gynecologic malignancy and over 28,000 women will succumb to their disease. For patients with an isolated locoregional recurrence after primary therapy, surgical resection may sometimes provide a chance of cure. To optimize the chance of local control intraoperative radiation therapy (IORT) has been used. The combination of salvage surgery and IORT has resulted in reasonable control in the IORT field. The addition of external beam radiation to limited volumes seems to result in improved disease control over surgery and IORT alone. Side effects are closely related to radical surgery, although neuropathy is seen more frequently after IORT; especially if doses of >20Gy are prescribed. Margin status remains critical, even with IORT.

Molecular genetics and metabolism, Jan 8, 2015

Sandhoff disease (SD) is a fatal neurodegenerative disease caused by a mutation in the enzyme β-N... more Sandhoff disease (SD) is a fatal neurodegenerative disease caused by a mutation in the enzyme β-N-acetylhexosaminidase. Children with infantile onset SD develop seizures, loss of motor tone and swallowing problems, eventually reaching a vegetative state with death typically by 4years of age. Other symptoms include vertebral gibbus and cardiac abnormalities strikingly similar to those of the mucopolysaccharidoses. Isolated fibroblasts from SD patients have impaired catabolism of glycosaminoglycans (GAGs). To evaluate mucopolysaccharidosis-like features of the feline SD model, we utilized radiography, MRI, echocardiography, histopathology and GAG quantification of both central nervous system and peripheral tissues/fluids. The feline SD model exhibits cardiac valvular and structural abnormalities, skeletal changes and spinal cord compression that are consistent with accumulation of GAGs, but are much less prominent than the severe neurologic disease that defines the humane endpoint (4....

Journal of Lipid Research, 2015

Personality and Individual Differences, 2009

This paper reports a single study in which individual differences in visual processing were asses... more This paper reports a single study in which individual differences in visual processing were assessed in comparison with participants' ability to identify a culprit from a lineup. There were two parts to the study, separated by several weeks. In the first part, participants were ...

Topics in magnetic resonance imaging : TMRI, 2006

Until 30 years ago, radiation oncology, previously known as therapeutic radiology, was one of the... more Until 30 years ago, radiation oncology, previously known as therapeutic radiology, was one of the subspecialties of radiology. It was an era in which radiation therapy planning was performed using plain radiograph images and clinical setups. After the rapid growth and ...

American journal of hypertension, 2008

Venous capacitance plays an important role in circulatory homeostasis. A number of reports have s... more Venous capacitance plays an important role in circulatory homeostasis. A number of reports have suggested an effect of estrogen on venous function. This study tested the hypothesis that ovariectomy would increase venous tone in the female spontaneously hypertensive rat (SHR) via autonomic mechanisms. Five-week-old female SHR were subjected to sham operation (Sham) or ovariectomy (OVX). At 10 weeks of age, the rats were instrumented for the measurement of arterial and venous pressure. A balloon catheter was advanced into the right atrium. Mean circulatory filling pressure (MCFP), an index of venous tone, was calculated. Mean arterial pressure (MAP), heart rate (HR), and MCFP were recorded from conscious rats. Postsynaptic adrenergic responsiveness was assessed by constructing cumulative dose-response curves to norepinephrine (NE). MAP was not significantly affected by ovariectomy (Sham 127 +/- 6 mm Hg vs. OVX 130 +/- 3 mm Hg). HR also was not different between groups (Sham 409 +/- 11...

Current opinion in critical care, 2009

The present study describes the use of serial severity scores to predict death in ICU patients an... more The present study describes the use of serial severity scores to predict death in ICU patients and compares the results with previously published literature on this topic. Predicting mortality in critically ill patients has tremendous significance and methods to do so accurately have been studied for decades. The ability to accurately predict death impacts medical therapies, triaging, end-of-life care, and many other aspects of ICU care. There are many methods in existence to help physicians predict mortality, but most are not very accurate on an individual basis. The main tools available are severity scores, published outcomes data, and personal experience and all of them have significant limitations. One strategy that has been shown to be effective in accurately predicting death is to use serial severity scoring during the patient's ICU admission. Recently, a retrospective study done on a large cohort of ICU patients at a single institution showed very high specificity in pred...

Journal of visualized experiments : JoVE, Jan 9, 2012

Microtubules are cytoskeletal polymers which play a role in cell division, cell mechanics, and in... more Microtubules are cytoskeletal polymers which play a role in cell division, cell mechanics, and intracellular transport. Each of these functions requires microtubules that are stiff and straight enough to span a significant fraction of the cell diameter. As a result, the microtubule persistence length, a measure of stiffness, has been actively studied for the past two decades(1). Nonetheless, open questions remain: short microtubules are 10-50 times less stiff than long microtubules(2-4), and even long microtubules have measured persistence lengths which vary by an order of magnitude(5-9). Here, we present a method to measure microtubule persistence length. The method is based on a kinesin-driven microtubule gliding assay(10). By combining sparse fluorescent labeling of individual microtubules with single particle tracking of individual fluorophores attached to the microtubule, the gliding trajectories of single microtubules are tracked with nanometer-level precision. The persistence...

Gynecologic oncology, 2014

To determine whether intra-operative radiation therapy (IORT) at the time of pelvic exenteration ... more To determine whether intra-operative radiation therapy (IORT) at the time of pelvic exenteration (PE) or laterally extended endopelvic resection (LEER) improves progression-free survival (PFS) in patients with recurrent, previously irradiated gynecologic cancers. We conducted a single institution retrospective review of patients who had undergone a complete PE for locally recurrent gynecologic cancer. Demographic and clinicopathologic data were collected. 32 patients were identified (2000-2012); 21 (66%) cervical cancer, 8 (25%) vaginal, and 3 (9%) vulvar cancer. All patients were previously irradiated. Twenty-one (66%) received IORT. Mean age was 51. Eight patients had a LEER, all with IORT. Median PFS and OS, respectively, for those with PE alone was 33 and 41 vs. 10 and 10 months for PE+IORT compared to 9 and 17 months for LEER+IORT (P=.04). Increasing tumor size negatively impacted PFS (hazard ratio 1.3; 95%CI 1.12-1.52). Margin status was not associated with survival. No patien...

Theriogenology, Jan 15, 2015

GnRH receptors play vital roles in mammalian reproduction via regulation of gonadotropin secretio... more GnRH receptors play vital roles in mammalian reproduction via regulation of gonadotropin secretion, which is essential for gametogenesis and production of gonadal steroids. GnRH receptors for more than 20 mammalian species have been sequenced, including human, mouse, and dog. This study reports the molecular cloning and sequencing of GnRH receptor (GnRHR) cDNA from the pituitary gland of the domestic cat, an important species in biomedical research. Feline GnRHR cDNA is composed of 981 nucleotides and encodes a 327 amino acid protein. Unlike the majority of mammalian species sequenced so far, but similar to canine GnRHR, feline GnRHR protein lacks asparagine in position three of the extracellular domain of the protein. At the amino acid level, feline GnRHR exhibits 95.1% identity with canine, 93.8% with human, and 88.9% with mouse GnRHR. Comparative sequence analysis of GnRHRs for multiple mammalian species led to resequencing of canine GnRHR, which differed from that previously pub...

Visual Cognition, 2010

It has frequently been reported that recognition performance is impaired when faces are presented... more It has frequently been reported that recognition performance is impaired when faces are presented in an inverted rather than upright orientation, a phenomenon termed the face inversion effect (FIE). Extending previous work on this topic, the current investigation explored whether individual differences in global precedence—the propensity to process nonfacial stimuli in a configural manner—impacts memory for faces. Based on performance

Urologic Oncology: Seminars and Original Investigations, 2012

To assess prostate-specific antigen response after definitive radiotherapy in a patient with loca... more To assess prostate-specific antigen response after definitive radiotherapy in a patient with localized Skene's gland adenocarcinoma resembling prostate adenocarcinoma.

Seminars in Liver Disease, 1985

Venous bypass restores normal hemodynamic physiology during the critical anhepatic phase of ortho... more Venous bypass restores normal hemodynamic physiology during the critical anhepatic phase of orthotopic transplantation of the liver. Its routine use in adults undergoing transplantation in Pittsburgh has resulted in lower operative blood losses, a lower frequency of postoperative renal failure, and a greater probability of survival for all but the highest risk patients. Because it allows for a longer anhepatic phase, the surgeon has the option of tailoring the native hepatectomy to the needs of the individual case, even to the point, in difficult cases, of obtaining most of the hemostasis after removal of the native liver, but before sewing in the donor organ. Selective use of bypass in children may offer similar advantages.

The Southwestern Naturalist, 2014

ABSTRACT The variable platyfish (Xiphophorus variatus), native to Gulf Coast drainages of norther... more ABSTRACT The variable platyfish (Xiphophorus variatus), native to Gulf Coast drainages of northern Mexico, is a popular aquarium fish with a long history of introduction globally. We document the first Texas occurrence of this species, and its persistence in highly urban Waller Creek in the city of Austin since at least 2004. The population appears to be limited to Waller Creek, having not yet been found in neighboring creeks where similar habitat exists. We observed individuals in situ and in the lab surviving in 7°C water, well below published thermal minima, and report its persistence through one of the coldest winters in Austin's recorded history. Its persistence may be due to a combination of its cold tolerance and the presence of thermal refuges. In the lab we found that individuals purchased in a local pet store and individuals from Waller Creek had the same cold tolerance.

Hydrobiologia, 2008

We report the results of a 3-year study of ichthyoplankton in the lower Savannah River and its co... more We report the results of a 3-year study of ichthyoplankton in the lower Savannah River and its coastal plain tributaries. Sampling was weekly from February through July in 1983, 1984 and 1985. Ichthyoplankton transport was used as an estimate of ichthyoplankton production. Ichthyoplankton transport in the river, for both total and most common taxa, was highest in 1983 and lowest

1999 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (Cat. No.99TH8399), 1999

Abstract Four servo loop designs for disk drive dual-stage actuatqr ,systems are studied. The cha... more Abstract Four servo loop designs for disk drive dual-stage actuatqr ,systems are studied. The characteristics and benefits of-each design are Giscussed. A parallel loop structure has been designed for a dual loop system with suspension based piezoelectric micro-actuators. ...

American journal of cardiovascular disease, 2015

Alteration of ubiquitin-proteasome system (UPS) mediated protein degradation has been implicated ... more Alteration of ubiquitin-proteasome system (UPS) mediated protein degradation has been implicated in the progression from a large subset of heart disease to congestive heart failure, rendering it extremely important to elucidate the cellular and molecular mechanism by which the UPS is regulated. Cullin-RING ligases (CRLs) represent the largest family of ubiquitin ligases crucial for UPS-dependent proteolysis. Serving as a cullin deneddylase, the COP9 signalosome (CSN) regulates the activity and assembly of CRLs. In the past several years, emerging studies have begun to unveil the role of the CSN and some of the CRLs in cardiomyocytes or the heart under physiological and pathological conditions. This review article will highlight and analyze these recent progresses and provide the author's perspective on the future directions for this research field.

American journal of cardiovascular disease, 2015

Disorders of vascular function contribute importantly to cardiovascular disease which represents ... more Disorders of vascular function contribute importantly to cardiovascular disease which represents a substantial cause of morbidity and mortality worldwide. An emerging paradigm in the study of cardiovascular diseases is that protein ubiquitination and turnover represent key pathological mechanisms. Our understanding of these processes in the vasculature is growing but remains incomplete. Since protein ubiquitination and turnover can represent a terminal event in the life of a given protein, entry into these pathways must be highly regulated. However, at present understanding of these regulatory mechanisms, particularly in the vasculature, is fragmentary. The COP9 (constitutive photomorphogenic mutant 9) signalosome (CSN) is a heteromeric protein complex implicated in the control of protein degradation. The CSN participates critically in the control of Cullin Ring Ligases (CRLs), at least in part via the detachment of a small protein, Nedd8 (deneddylation). CRLs are one of the largest...

Gynecologic oncology, Jan 29, 2015

Every year almost 95,000 women are diagnosed with a gynecologic malignancy and over 28,000 women ... more Every year almost 95,000 women are diagnosed with a gynecologic malignancy and over 28,000 women will succumb to their disease. For patients with an isolated locoregional recurrence after primary therapy, surgical resection may sometimes provide a chance of cure. To optimize the chance of local control intraoperative radiation therapy (IORT) has been used. The combination of salvage surgery and IORT has resulted in reasonable control in the IORT field. The addition of external beam radiation to limited volumes seems to result in improved disease control over surgery and IORT alone. Side effects are closely related to radical surgery, although neuropathy is seen more frequently after IORT; especially if doses of >20Gy are prescribed. Margin status remains critical, even with IORT.

Molecular genetics and metabolism, Jan 8, 2015

Sandhoff disease (SD) is a fatal neurodegenerative disease caused by a mutation in the enzyme β-N... more Sandhoff disease (SD) is a fatal neurodegenerative disease caused by a mutation in the enzyme β-N-acetylhexosaminidase. Children with infantile onset SD develop seizures, loss of motor tone and swallowing problems, eventually reaching a vegetative state with death typically by 4years of age. Other symptoms include vertebral gibbus and cardiac abnormalities strikingly similar to those of the mucopolysaccharidoses. Isolated fibroblasts from SD patients have impaired catabolism of glycosaminoglycans (GAGs). To evaluate mucopolysaccharidosis-like features of the feline SD model, we utilized radiography, MRI, echocardiography, histopathology and GAG quantification of both central nervous system and peripheral tissues/fluids. The feline SD model exhibits cardiac valvular and structural abnormalities, skeletal changes and spinal cord compression that are consistent with accumulation of GAGs, but are much less prominent than the severe neurologic disease that defines the humane endpoint (4....

Journal of Lipid Research, 2015

Personality and Individual Differences, 2009

This paper reports a single study in which individual differences in visual processing were asses... more This paper reports a single study in which individual differences in visual processing were assessed in comparison with participants' ability to identify a culprit from a lineup. There were two parts to the study, separated by several weeks. In the first part, participants were ...

Topics in magnetic resonance imaging : TMRI, 2006

Until 30 years ago, radiation oncology, previously known as therapeutic radiology, was one of the... more Until 30 years ago, radiation oncology, previously known as therapeutic radiology, was one of the subspecialties of radiology. It was an era in which radiation therapy planning was performed using plain radiograph images and clinical setups. After the rapid growth and ...

American journal of hypertension, 2008

Venous capacitance plays an important role in circulatory homeostasis. A number of reports have s... more Venous capacitance plays an important role in circulatory homeostasis. A number of reports have suggested an effect of estrogen on venous function. This study tested the hypothesis that ovariectomy would increase venous tone in the female spontaneously hypertensive rat (SHR) via autonomic mechanisms. Five-week-old female SHR were subjected to sham operation (Sham) or ovariectomy (OVX). At 10 weeks of age, the rats were instrumented for the measurement of arterial and venous pressure. A balloon catheter was advanced into the right atrium. Mean circulatory filling pressure (MCFP), an index of venous tone, was calculated. Mean arterial pressure (MAP), heart rate (HR), and MCFP were recorded from conscious rats. Postsynaptic adrenergic responsiveness was assessed by constructing cumulative dose-response curves to norepinephrine (NE). MAP was not significantly affected by ovariectomy (Sham 127 +/- 6 mm Hg vs. OVX 130 +/- 3 mm Hg). HR also was not different between groups (Sham 409 +/- 11...

Current opinion in critical care, 2009

The present study describes the use of serial severity scores to predict death in ICU patients an... more The present study describes the use of serial severity scores to predict death in ICU patients and compares the results with previously published literature on this topic. Predicting mortality in critically ill patients has tremendous significance and methods to do so accurately have been studied for decades. The ability to accurately predict death impacts medical therapies, triaging, end-of-life care, and many other aspects of ICU care. There are many methods in existence to help physicians predict mortality, but most are not very accurate on an individual basis. The main tools available are severity scores, published outcomes data, and personal experience and all of them have significant limitations. One strategy that has been shown to be effective in accurately predicting death is to use serial severity scoring during the patient's ICU admission. Recently, a retrospective study done on a large cohort of ICU patients at a single institution showed very high specificity in pred...

Journal of visualized experiments : JoVE, Jan 9, 2012

Microtubules are cytoskeletal polymers which play a role in cell division, cell mechanics, and in... more Microtubules are cytoskeletal polymers which play a role in cell division, cell mechanics, and intracellular transport. Each of these functions requires microtubules that are stiff and straight enough to span a significant fraction of the cell diameter. As a result, the microtubule persistence length, a measure of stiffness, has been actively studied for the past two decades(1). Nonetheless, open questions remain: short microtubules are 10-50 times less stiff than long microtubules(2-4), and even long microtubules have measured persistence lengths which vary by an order of magnitude(5-9). Here, we present a method to measure microtubule persistence length. The method is based on a kinesin-driven microtubule gliding assay(10). By combining sparse fluorescent labeling of individual microtubules with single particle tracking of individual fluorophores attached to the microtubule, the gliding trajectories of single microtubules are tracked with nanometer-level precision. The persistence...

Gynecologic oncology, 2014

To determine whether intra-operative radiation therapy (IORT) at the time of pelvic exenteration ... more To determine whether intra-operative radiation therapy (IORT) at the time of pelvic exenteration (PE) or laterally extended endopelvic resection (LEER) improves progression-free survival (PFS) in patients with recurrent, previously irradiated gynecologic cancers. We conducted a single institution retrospective review of patients who had undergone a complete PE for locally recurrent gynecologic cancer. Demographic and clinicopathologic data were collected. 32 patients were identified (2000-2012); 21 (66%) cervical cancer, 8 (25%) vaginal, and 3 (9%) vulvar cancer. All patients were previously irradiated. Twenty-one (66%) received IORT. Mean age was 51. Eight patients had a LEER, all with IORT. Median PFS and OS, respectively, for those with PE alone was 33 and 41 vs. 10 and 10 months for PE+IORT compared to 9 and 17 months for LEER+IORT (P=.04). Increasing tumor size negatively impacted PFS (hazard ratio 1.3; 95%CI 1.12-1.52). Margin status was not associated with survival. No patien...

Theriogenology, Jan 15, 2015

GnRH receptors play vital roles in mammalian reproduction via regulation of gonadotropin secretio... more GnRH receptors play vital roles in mammalian reproduction via regulation of gonadotropin secretion, which is essential for gametogenesis and production of gonadal steroids. GnRH receptors for more than 20 mammalian species have been sequenced, including human, mouse, and dog. This study reports the molecular cloning and sequencing of GnRH receptor (GnRHR) cDNA from the pituitary gland of the domestic cat, an important species in biomedical research. Feline GnRHR cDNA is composed of 981 nucleotides and encodes a 327 amino acid protein. Unlike the majority of mammalian species sequenced so far, but similar to canine GnRHR, feline GnRHR protein lacks asparagine in position three of the extracellular domain of the protein. At the amino acid level, feline GnRHR exhibits 95.1% identity with canine, 93.8% with human, and 88.9% with mouse GnRHR. Comparative sequence analysis of GnRHRs for multiple mammalian species led to resequencing of canine GnRHR, which differed from that previously pub...

Visual Cognition, 2010

It has frequently been reported that recognition performance is impaired when faces are presented... more It has frequently been reported that recognition performance is impaired when faces are presented in an inverted rather than upright orientation, a phenomenon termed the face inversion effect (FIE). Extending previous work on this topic, the current investigation explored whether individual differences in global precedence—the propensity to process nonfacial stimuli in a configural manner—impacts memory for faces. Based on performance

Urologic Oncology: Seminars and Original Investigations, 2012

To assess prostate-specific antigen response after definitive radiotherapy in a patient with loca... more To assess prostate-specific antigen response after definitive radiotherapy in a patient with localized Skene's gland adenocarcinoma resembling prostate adenocarcinoma.

Seminars in Liver Disease, 1985

Venous bypass restores normal hemodynamic physiology during the critical anhepatic phase of ortho... more Venous bypass restores normal hemodynamic physiology during the critical anhepatic phase of orthotopic transplantation of the liver. Its routine use in adults undergoing transplantation in Pittsburgh has resulted in lower operative blood losses, a lower frequency of postoperative renal failure, and a greater probability of survival for all but the highest risk patients. Because it allows for a longer anhepatic phase, the surgeon has the option of tailoring the native hepatectomy to the needs of the individual case, even to the point, in difficult cases, of obtaining most of the hemostasis after removal of the native liver, but before sewing in the donor organ. Selective use of bypass in children may offer similar advantages.