Damir Sapunar | University of Split, School of Medicine (original) (raw)

Papers by Damir Sapunar

ST-OPEN, 2024

Aim: Beside its catastrophic consequences for Ukraine, the Russian aggression has had a major imp... more Aim: Beside its catastrophic consequences for Ukraine, the Russian aggression has had a major impact on Russian society. The article explores and reflects on the experience of a 23-year-old student in Russia during the first year of the war in Ukraine (2022) which elucidates the moral conflict of dealing with close relatives who hold a different political view on the conflict. The first author uses autoethnography to describe the lived experience of navigating the nuances of daily life, grappling with propaganda, and conflicting feelings toward close relatives. In particular, the author is questioning how one must act in times of peril and moral demise.
Methods: We employed autoethnographic collaborative research to explore the first author’s narrative stemming from her personal experience of being a citizen of a country that inflicted a war on another country. The examination of the narrative was conducted collaboratively with another researcher (DS) to enhance comprehension regarding how personal context interacts with social, political, and cultural factors.
Results: The presented story is the first author’s exploration and attempt to position herself in morally challenging situations, while also considering the everyday elements of the war, including the silencing effects of political oppression, propaganda, political censorship, and wartime atrocities. Within this consideration, the first author reflects on the Russian aggression on Ukraine and its implications through the lens of her own experience with propaganda, all while learning to cope with a moral injury inflicted by the closest member of the family.
Conclusion: The Russian political system has major consequences for young adults' ability to uphold a normal life. Exposure to propaganda and fake news presents a constant threat of destroying the fine fabric of interpersonal relationships and imposing moral injury by the inability to act because of an oppressive political system.

Brain Research, 2005

In order to clarify the physiologic role of NPY in sensory processing, we obtained intracellular ... more In order to clarify the physiologic role of NPY in sensory processing, we obtained intracellular recordings of DRG neurons from wild type (WT) and NPY overexpressing transgenic rats (NPY-TG) before and after injury. We investigated medium and large diameter DRG neurons since upregulation of NPY peptide following the nerve injury occurs primarily in those cells. Neurons were classified as Aa/h and Ay using conduction velocity and action potential duration. Prior to the injury, Aa/h neurons of NPY-TG rats conducted more slowly and had a more brief AHP than similar cells from the WT group. Ay neurons at baseline conducted faster in TG animals compared to WT. Ligation of the 5th lumbar spinal nerve (SNL) produced certain changes in Aa/h cells that were evident only in the TG group. These include increased refractory period, increased input resistance, AHP prolongation and a depolarizing shift in threshold for AP initiation. The expected injury-induced CV slowing was not seen in NPY-TG Aa/h cells. In the Ay cell group, injury produced a depolarizing shift in the resting membrane potential, an increase in AP duration and decrease in AHP and refractory period duration only in WT rats, while NPY-TG cells lacked these injury-induced changes. Behavior tests showed diminished sensory response to nerve injury in NPY-TG rats, i.e., shorter duration of enhanced pain-related behavior and attenuation of contralateral effect. In conclusion, our observations suggest that NPY overexpression leads to reduced neuronal activity following nerve injury in a cell-specific manner. D

Acta Neuropathologica, 1996

Differences in histological appearance between the cranial and caudal parts of the spinal cord an... more Differences in histological appearance between the cranial and caudal parts of the spinal cord and associated axial organs were analyzed in 9- and 15-week-old human dysraphic fetuses and compared with normal fetuses. In human development the cranial part of the neural tube down to the lumbosacral level forms during primary neurulation, while its caudal part results from secondary neurulation. In the 9-week fetus with cervical spina bifida, the cranial spinal cord displayed a variety of morphological changes along the cranio-caudal axis. Spinal cord in the upper cervical region transformed into the area cerebrovasculosa, while the lower cervical and thoracic levels showed only disturbed differentiation of the cell layers and roof plate. The degree of the cranial spinal cord dysmorphogenesis correlated with anomalies of the underlying notochord and vertebral column. The caudal to lumbosacral region of the spinal cord appeared normal. In the case of the 15-week-old fetus with complete dysraphia, the area cerebrovasculosa was found along the whole extent of the cranial spinal cord, while more caudally, all axial organs showed a normal histological structure. Our findings confirmed a different origin for the cranial and caudal parts of the human spinal cord. The appearance of dysraphic disorders corresponded to the time of primary neurulation; therefore, they resulted in the faulty formation of the cranial spinal cord. Normally formed caudal spinal cord appears during secondary neurulation at later developmental stages.

Journal of Molecular Histology, 2008

The distribution of the bcl-2, bax and caspase-3 proteins was investigated in the cells of develo... more The distribution of the bcl-2, bax and caspase-3 proteins was investigated in the cells of developing human spinal ganglia. Paraffin sections of 10 human conceptuses between 5th and 9th gestational weeks were analysed morphologically, immunohistochemically and by TUNEL-method. Cells positive to caspase-3 had brown stained nuclei or nuclear fragmentations. At earliest stages, 6% of ganglion population were caspase-3 positive cells. Later on, a significant increase in number of caspase-3 positive cells appeared, particularly in the ventral part of ganglia (12%), and subsequently decreased to 6%. TUNEL-positive cells had the same distribution pattern as caspase-3 positive cells. Bax-positive cells followed the developmental pattern similar to caspase-3 cells, changing in range between 20% and 32%. There were 8% of bcl-2 positive cells at earliest stages. They increased significantly in dorsal part of the ganglion during the 7th week (28%), and than dropped to 15% by the end of the 8th week. These findings suggest a ventro-dorsal course of development in human spinal ganglia. Number of bcl-2, bax and caspase-3 positive cells changed in a temporally and spatially restricted manner, coincidently with ganglion differentiation. While apoptosis might control cell number, bcl-2 could act in suppression of apoptosis and enhancement of cell differentiation.

Reproduction Fertility and Development, 1996

Chest, 1994

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Anesthesiology, 2005

Painful peripheral nerve injury results in disordered sensory neuron function that contributes to... more Painful peripheral nerve injury results in disordered sensory neuron function that contributes to the pathogenesis of neuropathic pain. However, the relative roles of neurons with transected axons versus intact adjacent neurons have not been resolved. An essential first step is identification of electrophysiologic changes in these two neuronal populations after partial nerve damage. Twenty days after spinal nerve ligation (SNL), intracellular recordings were obtained from axotomized fifth lumbar (L5) dorsal root ganglion neurons and adjacent, intact L4 neurons, as well as from control neurons and others subjected to sham-SNL surgery. Pronounced electrophysiologic changes were seen only in L5 neurons after SNL. Both Aalpha/beta and Adelta neuron types showed increased action potential duration, decreased afterhyperpolarization amplitude and duration, and decreased current threshold for action potential initiation. Aalpha/beta neurons showed resting membrane potential depolarization, and increased repetitive firing during sustained depolarization developed in Adelta neurons. The afterhyperpolarization duration in neurons with C fibers shortened after axotomy. In contrast to the axotomized L5 neurons, neighboring L4 neurons showed no changes in action potential duration, afterhyperpolarization dimensions, or excitability after SNL. Depolarization rate (dV/dt) increased after SNL in L4 Aalpha/beta and Adelta neurons but decreased in L5 neurons. Time-dependent rectification during hyperpolarizing current injection (sag) was greater after SNL in Aalpha/beta L4 neurons compared with L5. Sham-SNL surgery produced only a decreased input resistance in Aalpha/beta neurons and a decreased conduction velocity in medium-sized cells. In the L5 ganglion after axotomy, a novel set of neurons, consisting of 24% of the myelinated population, exhibited long action potential durations despite myelinated neuron conduction velocities, particularly depolarized resting membrane potential, low depolarization rate, and absence of sag. These findings indicate that nerve injury-induced electrical instability is restricted to axotomized neurons and is absent in adjacent intact neurons.

Spinal afferent neurons, with endings in the intestinal mesenteries, have been shown to respond t... more Spinal afferent neurons, with endings in the intestinal mesenteries, have been shown to respond to changes in vascular perfusion rates. The mechanisms underlying this sensitivity were investigated in an in vitro preparation of the mesenteric fan devoid of connections with the gut wall. Afferent discharge increased when vascular perfusion was stopped ("flow off"), a response localized to the terminal vessels just prior to where they entered the gut wall. The flow-off response was compared following pharmacological manipulations designed to determine direct mechanical activation from indirect mechanisms via the vascular endothelium or muscle. Under Ca(2+)-free conditions, responses to flow off were significantly augmented. In contrast, the myosin light chain kinase inhibitor wortmannin (1 microM, 20 min) did not affect the flow-off response despite blocking the vasoconstriction evoked by 10 microM l-phenylephrine. This ruled out active tension, generated by vascular smooth muscle, in the response to flow off. Passive changes caused by vessel collapse during flow off were speculated to affect sensory nerve terminals directly. The flow-off response was not affected by the N-, P-, and Q-type Ca(2+) channel blocker omega-conotoxin MVIIC (1 muM intra-arterially) or the P2X receptor/ion channel blocker PPADS (50 microM). However, ruthenium red (50 microM), a blocker of nonselective cation channels, greatly reduced the flow-off response and also abolished the vasodilator response to capsaicin. Our data support the concept that mesenteric afferents sense changes in vascular flow during flow off through direct mechanisms, possibly involving nonselective cation channels. Passive distortion in the fan, caused by changes in blood flow, may represent a natural stimulus for these afferents in vivo.

International Journal of Behavioral Medicine

Background Parents’ pain behavior is associated with the way their children experience and expres... more Background Parents’ pain behavior is associated with the way their children experience and express pain. Purpose We hypothesized that there is a positive association between levels of pain catastrophizing in parents and their adult children. Method Study included 285 participants, 100 patients, 85 spouses, and 100 adult children from 100 families. Pain catastrophizing was assessed with the Croatian version of Pain Catastrophizing Scale. Patients’ pain intensity was measured with the visual analogue scale. Results Significant positive correlation was found between pain catastrophizing of adult children and both of their parents. Regression analysis was conducted to test for the role of parents’ pain catastrophizing scores in explaining pain catastrophizing in their adult children. The results showed that parents’ pain catastrophizing scores explain results of their adult children, accounting for 20% of the variance. Conclusion The results from the present study indicate that there is a positive association between levels of pain catastrophizing in parents and their adult children. A family may have a specific cognitive style for coping with pain, which is associated to a child’s responses to pain experiences.

Anesthesiology, 2004

Behavioral criteria that confirm neuropathic pain in animal injury models are undefined. Therefor... more Behavioral criteria that confirm neuropathic pain in animal injury models are undefined. Therefore, the authors sought clinically relevant measures that distinguish pain behavior of rats with peripheral nerve injury from those with sham injury. The authors examined mechanical and thermal sensory sensitivity, comparing responses at baseline to responses after spinal nerve ligation (SNL group), sham nerve injury (sham group), or skin incision alone (control group). Substantial variance was evident in all sensory tests at baseline. After surgery, tests using brush, cold, or heat stimulation showed minimal distinctions between surgical groups. Postsurgical thresholds for flexion withdrawal from mechanical stimulation with von Frey fibers were decreased bilaterally in SNL and sham groups. In contrast, the probability of a complex hyperalgesia-type response with prolonged elevation, shaking, or licking of the paw was selectively increased on the ipsilateral side in the SNL group. Nonetheless, the effect of SNL on behavior was inconsistent, regardless of the sensory test. The behavioral measure that best distinguishes between SNL and sham groups and thereby best identifies animals with successful SNL-induced neuropathic pain is increased ipsilateral postsurgical probability of a hyperalgesia-type response to noxious mechanical stimulation. Using receiver operating characteristics analysis, mechanical hyperalgesia identifies a local SNL effect in approximately 60% of animals when specificity is required to be 90% or higher. Simple withdrawal from von Frey tactile stimulation, although frequently used, is not a valid measure of peripheral nerve injury pain in rats, whereas a complex hyperalgesic-type response is a specific neuropathy-induced behavior.

Medical Teacher, 2007

Background: According to data regarding number of physicians per 100 000 inhabitants, Croatia is ... more Background: According to data regarding number of physicians per 100 000 inhabitants, Croatia is below the European average. Under those circumstances, more attention needs to be devoted to Croatian medical schools and their applicants. Aims: This study sought to investigate admission trends of applicants to Croatian medical schools, analyse their demographics and motives for medical school enrollment. Methods: We collected admissions data of applicants to Croatian medical schools from 1979 to 2006. Motives for and against medical school enrollment were assessed in a survey of 1146 applicants (response rate 84%, 966/1146) and 98 final-year medical students (response rate 82%, 80/98) during July 2006. Results: The number of applicants to Croatian medical schools had been declining until 1995, it was lowest during the 1991-1995 war in Croatia and it has been rising from 1996 onwards. Majority of applicants in 2006/07 were women (69%). Most of the applicants attended general high schools. The applicants profess choosing a certain medical school for its quality and reputation, but we showed that they actually chose the closest school. The main motives for medical school enrollment were humanitarian and scientific, while main reasons against were perceived difficulty and financial burden. We showed that final-year medical students profess significantly lower interest in science and that they are less interested in altruistic aspects of medicine. Instead, great number of them would reconsider choosing medical studies again because of the corruption in medicine, fear of mistakes and uncertainty of employment. Conclusions: Following the admission trends in medical schools on a national level gives insight into the prospects of health care. Analysis of motives for and against medical school enrollment can provide guidelines for their improvement. Unless Croatia and other countries in transition devote more attention to recruitment, education and retention of physicians, the prospects of our healthcare are poor.

Anesthesiology, 2006

Reports of Ca(2+) current I(Ca) loss after injury to peripheral sensory neurons do not discrimina... more Reports of Ca(2+) current I(Ca) loss after injury to peripheral sensory neurons do not discriminate between axotomized and spared neurons. The spinal nerve ligation model separates axotomized from spared neurons innervating the same site. The authors hypothesized that I(Ca) loss is a result of neuronal injury, so they compared axotomized L5 dorsal root ganglion neurons to spared L4 neurons, as well as neurons from rats undergoing skin incision alone. After behavioral testing, dissociated neurons from L4 and L5 dorsal root ganglia were studied in both current and voltage patch clamp modes. The biophysical consequence of I(Ca) loss on the action potential was confirmed using selective I(Ca) antagonists. Data were grouped into small, medium, and large cells for comparison. Reduced I(Ca) was predominantly a consequence of axotomy (L5 after spinal nerve ligation) and was most evident in small and medium neurons. ICa losses were associated with action potential prolongation in small and medium cells, whereas the amplitude and duration of after hyperpolarization was reduced in medium and large neurons. Blockade with Ca(2+) channel antagonists showed that action potential prolongation and after hyperpolarization diminution were alike, attributable to the loss of I(Ca). Axotomy is required for I(Ca) loss. I(Ca) loss correlated with changes in the biophysical properties of sensory neuron membranes during action potential generation, which were due to I(Ca) loss leading to decreased outward Ca(2+)-sensitive K currents. Taken together, these results suggest that neuropathic pain may be mediated, in part, by loss of I(Ca) and the cellular processes dependent on Ca(2+).

Neuroscience Letters, 2003

ATP-sensitive potassium (K ATP ) currents were examined in dorsal root ganglion neurons from neur... more ATP-sensitive potassium (K ATP ) currents were examined in dorsal root ganglion neurons from neuropathic and control rats using wholecell voltage clamp recordings. K ATP channel openers (diazoxide and pinacidil) enhanced, and the blocker glibenclamide inhibited an outward current in control neurons in a manner dependent on the pipette ATP concentration. Analysis of reversal potentials showed that this current is carried by K þ ions. Outward current in cells from rats with peripheral nerve injury was not sensitive to modulators of K ATP channels. Gabapentin, a putative K ATP channel opener, had minimal effect on currents in either group of neurons. We conclude that normal primary afferent neurons express K ATP channels that conduct current which is eliminated by peripheral nerve injury. Gabapentin does not affect this current significantly. q

Journal of Neuroscience Methods, 2009

We sought an optimal method for targeted delivery into dorsal root ganglia (DRGs) for experimenta... more We sought an optimal method for targeted delivery into dorsal root ganglia (DRGs) for experimental studies, in terms of precision of delivery and avoidance of behavioral disturbances. We examined three approaches for injection into rat DRGs: percutaneous injection without surgical exposure, injection after deep exposure, and injection following deep exposure and partial laminectomy. Coomassie blue and Fast Blue were injected into DRGs for validation. At necropsy, the spread of Coomassie blue and Fast Blue was investigated under stereomicroscope and fluorescent microscope, respectively. We found that percutaneous approach did not provide any successful DRG injections. Deep exposure prior to intraganglionic injection provided variable results, but intraganglionic injection after deep exposure plus partial laminectomy was successful in 100% of attempts. Our subsequent skeletal analysis showed that the anatomical location of DRG is not compatible with successful DRG injection without surgical exposure. Neither of the methods using surgical exposure caused behavioral disturbances. Based on these results we conclude that partial laminectomy offers the most precise method of injecting DRG and does not produce behavioral evidence of nerve damage. Intraganglionic injection after deep exposure alone is less predictable, while percutaneous approaches only allow injection in the peripheral nerve.

Medical Education, 2010

Medical Education 2010: 44: 387–395Context Elective courses are a significant part of undergradu... more Medical Education 2010: 44: 387–395Context Elective courses are a significant part of undergraduate medical education throughout the world, but the value provided by these courses and the reasons for choosing particular elective courses have not been studied extensively.Objectives The aim of this study was to investigate medical and dental students’ experiences of elective courses in undergraduate medical education in Croatia and to gather students’ recommendations for the improvement of elective courses.Methods Medical and dental students studying under the Bologna curriculum were given a questionnaire in which they were asked for their opinions of elective courses and their suggestions as to how they might be improved. Data on elective courses were obtained from medical schools’ administrative offices.Results The survey response rate was 92% (834/903). Medical students gave elective courses an average grade of 3.44 out of 5, whereas dental students gave a lower average of 3.15. Students’ suggestions for change included introducing more practical work and recognising international student exchanges and attendance at conferences as elective options. A third of students indicated that teachers should be given additional training in leading elective courses. Analysis of the curriculum showed that elective courses in Croatian medical schools are very heterogeneous in terms of their content and the number of credits and assessment methods they involve, and are very conservative in that only structured courses are offered. Students cannot design their own courses or take more elective courses than represent 10% of their total number of credits.Conclusions Student opinion should be consulted when medical schools venture into the elective curriculum so that students can feel that they are really benefiting from these subjects. Students would welcome new and personally designed strands. Elective courses are a significant part of medical education and therefore their quality and purpose need to be assessed regularly in order to ensure that they meet students’ needs.

Background-Chronic neuropathic pain resulting from neuronal damage remains difficult to treat, in... more Background-Chronic neuropathic pain resulting from neuronal damage remains difficult to treat, in part due to incomplete understanding of underlying cellular mechanisms. We have previously shown that inward Ca 2+ flux (I Ca ) across the sensory neuron plasmalemma is decreased in a rodent model of chronic neuropathic pain, but the direct consequence of this loss of I Ca on function of the sensory neuron has not been defined. We therefore examined the extent to which altered membrane properties after nerve injury, especially increased excitability that may contribute to chronic pain, are attributable to diminished Ca 2+ entry.

Anesthesia and Analgesia, 2008

We have previously shown that a decrease of inward Ca 2+ flux (I Ca ) across the sensory neuron p... more We have previously shown that a decrease of inward Ca 2+ flux (I Ca ) across the sensory neuron plasmalemma, such as happens after axotomy, elevates neuronal excitability. From this, we predicted that increasing I Ca in injured neurons should correct their hyperexcitability, which we have tested during recording from A-type neurons in non-dissociated dorsal root ganglia after spinal nerve ligation, using an intracellular recording technique. When bath Ca 2+ level was elevated to promote I Ca , the afterhyperpolarization was decreased and repetitive firing was suppressed, which also followed amplification of Ca 2+ -activated K + current with selective agents NS1619 and NS309. Lowered external bath Ca 2+ concentration had opposite effects, similar to previous observations in uninjured neurons. These findings indicate that at least a part of the hyperexcitability of somatic sensory neurons after axotomy is attributable to diminished inward Ca 2+ flux, and that measures to restore I Ca may potentially be therapeutic for painful peripheral neuropathy.

Journal of Comparative Neurology, 2010

The enzyme calcium/calmodulin-dependent protein kinase II (CaMKII) is associated with memory and ... more The enzyme calcium/calmodulin-dependent protein kinase II (CaMKII) is associated with memory and its α isoform is critical for development of activity-induced synaptic changes. Therefore, we hypothesized that CaMKII is involved in altered function of dorsal root ganglion (DRG) neurons after neuronal injury. To test this hypothesis, Sprague–Dawley rats were made hyperalgesic by L5 and L6 spinal nerve ligation (SNL), and changes in total phosphorylated and unphosphorylated CaMKII (tCaMKII) and phosphorylated form of its α isoform (pCaMKIIα) were analyzed using immunochemistry in different subpopulations of DRG. SNL did not induce any changes in tCaMKII between experimental groups, while the overall percentage of pCaMKIIα-positive neurons in injured L5 DRG SNL (24.8%) decreased significantly when compared to control (41.7%). SNL did not change the percentage of pCaMKIIα/N52 colabeled neurons but decreased the percentage of N52-negative nonmyelinated neurons that expressed pCaMKIIα from 27% in control animals to 11% after axotomy. We also observed a significant decrease in the percentage of small nonpeptidergic neurons labeled with IB4 (37.6% in control vs. 4.0% in L5 SNL DRG), as well as a decrease in the percentage of pCaMKIIα/IB4 colabeled neurons in injured L5 DRGs (27% in control vs. 1% in L5 DRG of SNL group). Our results show that reduction in pCaMKIIα levels following peripheral injury is due to the loss of IB4-positive neurons. These results indicate that diminished afferent activity after axotomy may lead to decreased phosphorylation of CaMKIIα. J. Comp. Neurol. 518:64–74, 2010. © 2009 Wiley-Liss, Inc.

Anesthesia and Analgesia, 2009

BACKGROUND-Injury of a spinal nerve or dorsal root ganglion (DRG) during selective spinal nerve b... more BACKGROUND-Injury of a spinal nerve or dorsal root ganglion (DRG) during selective spinal nerve blocks is a potentially serious complication that has not been adequately investigated. Our hypothesis was that local anesthetic injection into these structures may result in an inflammatory response and hyperalgesia.

Anesthesia and Analgesia, 2008

ST-OPEN, 2024

Brain Research, 2005

Acta Neuropathologica, 1996

Journal of Molecular Histology, 2008

Reproduction Fertility and Development, 1996

Chest, 1994

services can be found online on the World Wide Web at:

Anesthesiology, 2005

International Journal of Behavioral Medicine

Anesthesiology, 2004

Medical Teacher, 2007

Anesthesiology, 2006

Neuroscience Letters, 2003

Journal of Neuroscience Methods, 2009

Medical Education, 2010

Anesthesia and Analgesia, 2008

Journal of Comparative Neurology, 2010

Anesthesia and Analgesia, 2009

Anesthesia and Analgesia, 2008