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Biomedical subjects

M Shamir

Publications and source records attributed to M Shamir.

17 recordsLinked to original sources
PubMed2005

Haematological and biochemical measurements in healthy, adult, free-ranging golden jackals (Canis aureus syriacus) held in captivity.

Blood from 31 healthy, free-ranging golden jackals held in captivity for seven days was collected while they were anaesthetised. Haematological and serum biochemical measurements were analysed and the 95 per cent confidence interval for each variable was compared with the reference value for domestic dogs. The measurements of their red blood cells were within the reference interval for dogs, but the jackals had higher white blood cell counts and eosinophil counts than dogs. The male jackals had a higher haematocrit, red blood cell count, mean corpuscular volume and mean corpuscular haemoglobin concentration, and a lower red blood cell distribution width than the female jackals. High activities of muscle enzymes were detected in many of the jackals, in several of which the activity of creatine kinase exceeded 5000 U/l; these were considered abnormal.

Animals↗
PubMed2001

Population coding in neuronal systems with correlated noise.

Neuronal representations of external events are often distributed across large populations of cells. We study the effect of correlated noise on the accuracy of these neuronal population codes. Our main question is whether the inherent error in the population code can be suppressed by increasing the size of the population N in the presence of correlated noise. We address this issue using a model of a population of neurons that are broadly tuned to an angular variable in two dimensions. The fluctuations in the neuronal activities are modeled as Gaussian noises with pairwise correlations that decay exponentially with the difference between the preferred angles of the correlated cells. We assume that the system is broadly tuned, which means that both the correlation length and the width of the tuning curves of the mean responses span a substantial fraction of the entire system length. The performance of the system is measured by the Fisher information (FI), which bounds its estimation error. By calculating the FI in the limit of a large N, we show that positive correlations decrease the estimation capability of the network, relative to the uncorrelated population. The information capacity saturates to a finite value as the number of cells in the population grows. In contrast, negative correlations substantially increase the information capacity of the neuronal population. These results are supplemented by the effect of correlations on the mutual information of the system. Our analysis provides an estimate of the effective number of statistically independent degrees of freedom, denoted N(eff), that a large correlated system can have. According to our theory N(eff) remains finite in the limit of a large N. Estimating the parameters of the correlations and tuning curves from experimental data in some cortical areas that code for angles, we predict that the number of effective degrees of freedom embedded in localized populations in these areas is less than or of the order of approximately 10(2).

Animals↗
PubMed2001

Effects of laser irradiation on the spinal cord for the regeneration of crushed peripheral nerve in rats.

BACKGROUND AND OBJECTIVE: The purpose of the present study was to examine the recovery of the crushed sciatic nerve of rats after low-power laser irradiation applied to the corresponding segments of the spinal cord. STUDY DESIGN/MATERIALS AND METHODS: After a crush injury to the sciatic nerve in rats, low-power laser irradiation was applied transcutaneously to corresponding segments of the spinal cord immediately after closing the wound by using 16 mW, 632 nm He-Ne laser. The laser treatment was repeated 30 minutes daily for 21 consecutive days. RESULTS: The electrophysiologic activity of the injured nerves (compound muscle action potentials--CMAPs) was found to be approximately 90% of the normal precrush value and remained so for up to a long period of time. In the control nonirradiated group, electrophysiologic activity dropped to 20% of the normal precrush value at day 21 and showed the first signs of slow recovery 30 days after surgery. The two groups were found to be significantly different during follow-up period (P < 0.001). CONCLUSION: This study suggests that low-power laser irradiation applied directly to the spinal cord can improve recovery of the corresponding insured peripheral nerve.

Animals↗
PubMed2001

Antibodies to selected canine pathogens and infestation with intestinal helminths in golden jackals (Canis aureus) in Israel.

Blood and fecal samples, collected from 46 healthy adult free-ranging golden jackals captured in two different locations in Israel, were examined. A serological Study was conducted to investigate the prevalence of circulating antibodies reacting with four common canine pathogens: canine distemper virus (CDV), canine parvovirus (CPV), Ehrlichia canis and Leishmania infantum. Faecal flotation and haematological tests were also performed. The seroprevalence of CPV, E. canis, CDV, and L. infantum were 72.3% (34/47), 54.3% (25/46), 52.2% (24/46), and 6.5% (3/46) respectively. Faecal flotation tests revealed a high prevalence of Ancylostoma caninum (13/17, 76%) and a low prevalence of Dipilidium caninum infestation. Examination of blood smears revealed Hepatazoon canis gamonts in one jackal. Golden jackals are among the most common free-ranging carnivores in Israel and neighboring countries. Their habitats are in proximity to densely populated areas and they bear close phylogenic relation to the domestic dog. These facts, combined with the high prevalence of the jackals' exposure to the major canine pathogens demonstrated in this study, suggest that they may serve as a reservoir for the transmission of certain diseases to domestic dogs.

Animals↗
PubMed2000

Thouless-anderson-palmer equations for neural networks

Previous derivation of the Thouless-Anderson-Palmer (TAP) equations for the Hopfield model by the cavity method yielded results that were inconsistent with those of the perturbation theory as well as the results derived by the replica theory of the model. Here we present a derivation of the TAP equation for the Hopfield model by the cavity method and show that it agrees with the form derived by perturbation theory. We also use the cavity method to derive TAP equations for the pseudoinverse neural network model. These equations are consistent with the results of the replica theory of these models.

Journal Article↗
PubMed1999

Pulse oximetry plethysmographic waveform during changes in blood volume.

Systolic pressure variation (SPV) and its dDown component have been shown to be sensitive factors in estimating intravascular volume in patients undergoing mechanical ventilation. In this study, ventilation-induced changes in pulse oximeter plethysmographic waveform were evaluated after removal and after reinfusion of 10% estimated blood volume. The plethysmographic waveform variation (SPVplet) was measured as the difference between maximal and minimal peaks of waveform during the ventilatory cycle, and expressed as a percentage of the signal amplitude during apnoea. dUp(plet) and dDown(plet) were measured as the distance between the apnoeic plateau and the maximal or minimal plethysmographic systolic waveform, respectively. Intravascular volume was changed by removal of 10% of estimated blood volume and followed by equal volume replacement with Haemaccel. A 10% decrease in blood volume increased SPVplet from mean 17.0 (SD 11.8)% to 31.6 (28.0)% (P = 0.005) and dDown(plet) from 8.7 (5.1)% to 20.5 (12.9)% (P = 0.0005) compared with baseline. Changes in plethysmographic waveform correlated with changes in arterial SPV and dDown (r = 0.85; P = 0.0009). In the absence of invasive arterial pressure monitoring, ventilation-induced waveform variability of the plethysmographic signal measured from pulse oximetry is a useful tool in the detection of mild hypovolaemia.

Adolescent↗
PubMed1999

Late onset of cerebellar abiotrophy in a Siamese cat.

A late onset of cerebellar degeneration was diagnosed in a one-and-a-half-year-old Siamese cat. The animal had been presented with mild ataxia involving all four limbs. Over the following two years, the signs gradually progressed to severe incoordination, a frequent tendency to fall and a head tremor. The neurological signs were consistent with a diffuse cerebellar lesion and the cat was euthanased. Profound and diffuse Purkinje cell loss was found on histopathological examination, but no aetiological agent was detected.

Age of Onset↗
PubMed1998

Successful resuscitation using aminophylline in refractory cardiac arrest with asystole.

Adenosine antagonists may have therapeutic potential in cardiopulmonary resuscitation. Aminophylline, a widely available adenosine antagonist, is not included in the Guidelines for Advanced Life Support by the European Resuscitation Council or the American Heart Association. This report addresses a case of out-of-hospital cardiac arrest caused by inferior wall myocardial infarction in which effective circulation was restored subsequent to aminophylline administration, after prolonged conventional resuscitation had resulted in asystole.

Aged↗
PubMed1997

[Fatal multiple organ system dysfunction associated with germanium metal used in complementary therapy].

The element germanium is widely distributed in nature. It is used in industry as a semiconductor and there have been a few attempts to use it in medicine. In the past few years 20 patients have been described in the literature as suffering from germanium overdosage. Like laboratory animals affected by the element, they suffer from renal failure and injury to other organs. We describe a 52-year old man given germanium to prevent recurrence of a brain tumor. He developed multiple organ dysfunction syndrome and died of intractable hyperdynamic shock. We call for caution regarding morbidity resulting from treatments believed safe.

Animals↗
PubMed1996

Reversal of fulminant-hepatitis-associated hypoglycaemia at the anhepatic stage during liver transplantation.

Hypoglycaemia is a known complication of fulminant hepatic failure. Massive destruction of liver tissue, along with hyperinsulinism and defective glucose storage in extrahepatic organs are some of the mechanisms contributing to the hypoglycaemia. We describe here a case of reversal of fulminant-hepatitis-associated hypoglycaemia at the anhepatic stage of liver transplantation. It is suggested that non-insulin hypoglycaemic factors secreted by the damaged liver may be responsible for this complication.

Child, Preschool↗
PubMedDate not supplied

A technique for management of bite wounds of the thoracic wall in small dogs.

Bite wounds of the chest wall in small dogs can extend into the thorax and can be associated with severe damage to chest wall muscles, ribs, and lungs. Two major problems associated with the management of these wounds are lack of sufficient muscle tissue for chest wall reconstruction, and difficulty draining the extensive dead space created in the chest wall. We describe a simple method to overcome these problems. The bite wound areas were surgically explored and all devitalized soft tissue was debrided. The pleural cavity was explored, intrathoracic injuries repaired, and a thoracic drainage tube was placed. Ribs in the injured area were stabilized in anatomic position by means of heavy gauge sutures passed around pairs of adjacent ribs, thus creating a scaffolding for soft tissues. Viable muscle and subcutaneous tissues were apposed as much as possible and the skin closed over the defect. Eleven small dogs were treated using this technique. All dogs had severe injuries to the thoracic wall muscles and eight dogs had multiple rib fractures. There was no evidence of chest wall instability in any of the dogs after surgery. Nine dogs survived the injury and were reevaluated 3 to 32 months after surgery. All were clinically normal. One dog developed wound infection and pyothorax, caused by insufficient debridement of injured muscle tissue, and died 10 days after surgery. A second dog died 24 hours postoperatively of undetermined causes.

Animals↗