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Biomedical subjects

B Hashemi

Publications and source records attributed to B Hashemi.

12 recordsLinked to original sources
PubMed2002

Experimental monitoring of hepatic glucose, lactate, and glutamate metabolism by microdialysis during surgical preparation of the liver hilus.

Mechanical liver manipulation can lead to hepatic microcirculation (MC) impairment. The pathobiochemical relevance of this phenomenon is not fully understood. Microdialysis (MD) allows a quantification of metabolic products in interstitial fluid, thus enabling analysis of the hepatic metabolic state during changes of liver perfusion. The aim of the study was to quantify the functional effects of standardized surgical liver preparation both on liver metabolism and microperfusion. Two groups of animals (pigs, n = 25) were formed: In the trial group (TG; n = 13) the liver was mobilized, followed by hilar preparation. In the control group (CG; n = 12) mobilization of the liver without hilar dissection was performed. Surgical manipulation was followed by an observation in both groups. Hepatic interstitial glucose, lactate, and glutamate concentrations were detected by MD and liver MC by thermodiffusion. During liver mobilization MC decreased significantly in both groups (TG; 86.7 +/- 2.0 to 73.4 +/- 2.3 ml/100 g min; and CG; 88.3 +/- 3.1 to 71.9 +/- 2.2 ml/100 g/min). In the trial group levels decreased further during hilar preparation reaching minimal values of 65.6 +/- 2.8. After preparation MC recovered to baseline. Glucose, lactate, and glutamate concentrations increased significantly during liver mobilization in the trial (glucose; 0.52 +/- 0.13 to 0.88 +/- 0.19 mmol/L; lactate; 0.34 +/- 0.07 to 0.54 +/- 0.07 mmol/L; glutamate; 34.5 +/- 3.6 to 52.6 +/- 8.0 micromol/L) and control group (glucose; 0.58 +/- 0.06 to 0.95 +/- 0.13 mmol/L; lactate; 0.30 +/- 0.06 to 0.49 +/- 0.07 mmol/L; glutamate; 32.9 +/- 2.36 to 56.1 +/- 5.12 micromol/L). Throughout hilus preparation maximum values could be measured in TG (glucose; 1.69 +/- 0.34; lactate; 0.90 +/- 0.18; glutamate; 63.5 +/- 7.2). After termination of mobilization or preparation baseline concentrations were reached again. MD allows monitoring of metabolic changes in hepatic parenchyma. Surgical liver preparation leads to changes of intrahepatic glucose, lactate, and glutamate levels (without alterations of parameters in systemic plasma) along with hepatic MC impairment. Reconstitution of hepatic MC was accompanied by rapid normalization of metabolic parameters. By measuring specific parameters, MD could prove to be of use for functional assessment of metabolic effects due to MC disturbances.

Animals↗
PubMed2000

[Surgical treatment of carpal tunnel syndrome in pregnancy: results from 314 cases].

A total of 314 hands of patients suffering from carpal tunnel syndrome (CTS) in pregnancy or puerperium were treated by carpal tunnel release. In 53% of these cases, other members of the family were also affected, usually the mother. Ninety-seven patients were operated upon at both hands. One hundred thirty-three operations were performed during pregnancy, mostly in the last trimester, and 181 during puerperium. In four patients, the operation was performed on both hands simultaneously. There were also 12 cases of associated De Quervain's tenosynovitis and ten trigger fingers. Severe night pain and/or permanent hypoesthesia was experienced by 93% of the patients. All patients were operated on with local anesthesia and in a bloodless field. The distal motor latency was 7 +/- 1.5 ms in cases with hypoesthesia and 4.9 +/- 1.75 ms without sensory loss. Of the patients, 98% reported good or excellent results of the operation during pregnancy via questionnaires. Since symptoms are often very severe in pregnancy and puerperium and the operation is well-tolerated by pregnant women and without risk to either mother or child, we recommend surgery, especially when sensory loss is present and motor latency is more than 5 ms.

Adolescent↗
PubMed2000

A new way for surgical education--development and evaluation of a computer-based training module.

Computer-based training (CBT) programs teach the material of a specific field and at the same time offer various ways of objectively assessing the knowledge gained. The interactive use of multi-media components such as text, graphics, animation, sound, digital slide shows, and videos as well as quizzes can theoretically facilitate the learning process. The aim of this study was the development and evaluation of a CBT-program by surgeons for student training. Using SuperCard, a teaching module for Distal Radius Fracture (DRF) was developed, which contains detailed clinical information. Video clips and vivid animations combine theoretical knowledge with practical experience. Fourth-year medical students (n = 103) were tested after using the module for 90 min. Other students (n = 47) served as the control group. In a 90 min lecture, DRF was discussed. CBT gained in all evaluated criteria (distinctiveness, detailed description, presentation of materials, structure, motivation for learning, time saved learning and memory retention) 15-20% better scores than the lecture. Although 82% of the students stated that their experience with computers was limited or insufficient, 100% found the use of CBT systems useful in student teaching. Most of them suggested the use of such programs as a method of exam preparation/self study (90%) or as a supplement to a lecture (40%). Based on these evaluations, CBT modules are an appropriate future teaching and learning system that is well accepted. In conclusion, the results of this study show that CBT-programs could be a valuable supplement to medical education. In addition, further development of CBT-programs and their use as information systems for surgical residency programs at universities can be suggested.

Adult↗
PubMed1999

Flow cytometric DNA analysis and chromosomal aberrations in malignant glioblastomas.

In this study we combined flow cytometry with fluorescence in situ hybridization to detect numerical aberrations in chromosomes. Fifty-nine human malignant gliomas were examined by flow cytometry for DNA-content and cell cycle analysis and for numerical aberrations of chromosome 1 by in situ hybridization using a chromosome specific centromere probe. Of the gliomas analysed, 42% were diploid and 58% showed aneuploid tumour cell populations. The DNA index was heterogeneous ranging from 1.0 to 2.3. The S-phase analysis showed proliferation activity from a very low range of 0.7% up to 17.0%. In general, diploid gliomas exhibited a lower S-phase activity than aneuploid gliomas. Of the aneuploid gliomas, 15% showed a peridiploid pattern with a DNA index mean of 1.1. In these peridiploid tumours a trisomy of chromosome 1 could be detected by fluorescence in situ hybridization (FISH). The frequency of trisomic chromosome 1 in malignant gliomas reflects a very slight increase in DNA index from diploid to peridiploid (DNA index 1.1). Comparison of chromosome numbers and DNA content gave good correlation. Also important, the results reflects the cell cycle, specifically the extent of S-phase activity. In general, cell proliferation of diploid and peridiploid gliomas is much less than in higher aneuploid gliomas. The analysis of DNA content may thus yield results with respect to the biological behaviour of tumours in general.

Chromosome Aberrations↗
PubMed1999

The scientific history of hydrocephalus and its treatment.

Hydrocephalus cases were regularly described by Hippocrates, Galen, and early and medieval Arabian physicians, who believed that this disease was caused by an extracerebral accumulation of water. Operative procedures used in ancient times are neither proven by skull findings today nor clearly reported in the literature. Evacuation of superficial intracranial fluid in hydrocephalic children was first described in detail in the tenth century by Abulkassim Al Zahrawi. In 1744, LeCat published findings on a ventricular puncture. Effective therapy required aseptic surgery as well as pathophysiological knowledge--both unavailable before the late nineteenth century. In 1881, a few years after the landmark study of Key and Retzius, Wernicke inaugurated sterile ventricular puncture and external CSF drainage. These were followed in 1891 by serial lumbar punctures (Quincke) and, in 1893, by the first permanent ventriculo-subarachnoid-subgaleal shunt (Mikulicz), which was simultaneously a ventriculostomy and a drainage into an extrathecal low pressure compartment. Between 1898 and 1925, lumboperitoneal, and ventriculoperitoneal, -venous, -pleural, and -ureteral shunts were invented, but these had a high failure rate due to insufficient implant materials in most cases. Ventriculostomy without implants (Anton 1908), with implants, and plexus coagulation initially had a very high operative mortality and were seldom successful in the long term, but gradually improved over the next decades. In 1949, Nulsen and Spitz implanted a shunt successfully into the caval vein with a ball valve. Between 1955 and 1960, four independent groups invented distal slit, proximal slit, and diaphragm valves almost simultaneously. Around 1960, the combined invention of artificial valves and silicone led to a worldwide therapeutic breakthrough. After the first generation of simple differential pressure valves, which are unable to drain physiologically in all body positions, a second generation of adjustable, autoregulating, antisiphon, and gravitational valves was developed, but their use is limited due to economical restrictions and still unsolved technical problems. At the moment, at least 127 different designs are available, with historical models and prototypes bringing the number to 190 valves, but most of these are only clones. In the 1990s, there has been a renaissance of endoscopic ventriculostomy, which is widely accepted as the method of first choice in adult patients with aquired or late-onset, occlusive hydrocephalus; in other cases the preference remains controversial. Both new methods, the second generation of valves as well as ventriculostomy, show massive deficits in evaluation. There is only one randomized study and no long-term evaluation.

Animals↗
PubMed1999

New valves--new dangers? 22 valves (38 probes) designed in the 'nineties in ultralong-term tests (365 days)'.

UNLABELLED: In the nineties, more than 30 valves have been launched, most are "clones", but some introduce new concepts (Diamond, SiphonGuard, PaediGAV). Of the 22 designs we tested, 20 have no previous tests and 3 are low-cost valves from Mexico (Dewimed), Zimbabwe (Harare-shunt) and England (Nottingham Shunt). 27 were tested using non-stop-perfusions for 365 days, 8 for 168-294 and 3 for 2 days. RESULTS: Ranking of the mean relative deviation: adjustable valves 19%, gravitational 34%, simple ball 51%, diaphragm 73%, distal slit 74% and autoregulating valves 121%. Ranking of physiological flow properties: gravitational > Equiflow > autoregulating > adjustable > ball > diaphragm > distal slit. SAFETY: The Equiflow were highly susceptible to external pressure. CONCLUSION: Most valves designed in the nineties showed inaccuracy, long-term-drifts, safety deficits and hydraulic mismanagement similar to more than 400 previously tested probes. With regard to accuracy and drift the ball designs were superior, but simple and adjustable ball valves are at risk of overdrainage. The gravitational ball valves (Cordis GCA, Miethke valves) showed the closest relation to physiological flow requirements.

Cerebrospinal Fluid Shunts↗
PubMed1997

[Computer-based training--a new method in surgical education and continuing education].

Computer-based training (CBT) programs teach the material of a specific field and at the same time offer various ways of objectively checking the knowledge gained. The interactive use of multimedia components, such as text, graphics, animation, sound, digital slide shows, videos and quizzes, facilitates the learning process. The aim of this study was the development and evaluation of a CBT program for use by surgeons teaching students. Using SuperCard, a teaching module for distal radius fracture (DRF) was developed, containing detailed clinical information. Video clips and vivid animation combine theoretical knowledge with practical experience. Fourth-year medical students (n = 103) were tested after using the module for 90 min. Other students (n = 47) served as the control group. In a 90-min lecture, DRF was discussed. In all evaluated criteria (distinctness, detailed description, presentation of materials, structure, motivation to learn, time saved while learning and memory retention), CBT gained 15-20% better scores than the lecture. Although 87% of the students stated that their experience with computers was limited or insufficient, 100% found the use of CBT systems helpful in student teaching. Most of them suggested the use of such programs as a exam preparation/self study method (90%) or as a supplement to a lecture (40%). Based on these evaluations, it is clear that CBT modules are an appropriate future teaching and learning system that will be well accepted. In conclusion, CBT programs should be integrated into medical education as a valuable supplement. With this aim, CBT systems should be developed and used at universities as an information system for the surgical residency program.

Achievement↗
PubMed1997

Involvement of GABAB receptors in the antinociception induced by baclofen in the formalin test.

1. The effect of GABA receptor antagonists on baclofen-induced antinociception was examined in rats using the formalin test. Intraperitoneal (IP) administration of different doses of baclofen (2.5-10 mg kg-1) to rats induced antinociception in both phases of the test. 2. The response was dose-dependent and the maximum response was observed with 10 mg kg-1 of the drug. Intracerebroventricular (ICV) injection of baclofen (0.5-20 micrograms/rat) also induced dose-dependent antinociception in the second phase of the formalin test. 3. The GABAB antagonist, phaclofen (1 mg kg-1, IP) but not the GABAA antagonists picrotoxin (1 mg kg-1, IP) and bicuculline (1.5 mg kg-1, IP), decreased the antinociception induced by both ICV and IP administration of baclofen. 4. It is concluded that baclofen antinociception in the formalin test is mediated through GABAB receptor activation.

Animals↗
PubMed1996

Effect of picrotoxin on antinociception in the formalin test.

Subcutaneous injection of diluted formalin (0.25 microliter of 0.5%) caused a biphasic pain response in mice. The first phase of pain was observed during the first 5 min., while the second phase occurred 10-30 min. after formalin administration. With the formalin test, it was found that the antinociception produced by the GABA-A antagonist, picrotoxin, and the GABA-B antagonist, phaclofen, was abolished when employed in combination. The opioid antagonist naloxone and antimuscarinic atropine also decreased the picrotoxin response. However, sulpiride, SCH 23390, phenoxybenzamine and propranolol did not alter the picrotoxin response. Administration of naloxone, sulpiride and propranolol showed a pain response. The data indicate that dopaminergic and adrenergic mechanisms may not be involved in the picrotoxin antinociceptive effect. However, postsynaptic GABA-A and GABA-B may be involved in the drug effect, and involvement of opioid or cholinergic systems can not be excluded.

Animals↗
PubMed1995

Effects of GABAergic drugs on physostigmine-induced yawning in rats.

In the present work the effects of GABA agonists and antagonists on yawning induced by physostigmine have been studied. Intraperitoneally (IP) injection of physostigmine (0.05-0.3 mg/kg) induced dose-related yawning in rats. The maximum yawning response was observed with 0.2 mg/kg of the drug. The GABA agonists muscimol (1-4 mg/kg) and baclofen (0.125-1 mg/kg) decreased yawning induced by physostigmine (0.2 mg/kg) dose dependently. Combination of both GABA agonists elicited greater inhibition of yawning. The GABA-A antagonists bicuculline or picrotoxin but not the GABA-B antagonist phaclofen reduced the inhibitory response induced by muscimol, whereas phaclofen but not bicuculline or picrotoxin reduced baclofen's inhibitory effect. Administration of bicuculline, picrotoxin or phaclofen also decreased the yawning induced by physostigmine. However, when the GABA-A and GABA-B antagonists were employed in combination, the inhibitory responses of both drugs were lost. It is concluded that GABA-A and/or GABA-B receptor stimulation may inhibit physostigmine-induced yawning.

Animals↗