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Biomedical subjects

Y Amit

Publications and source records attributed to Y Amit.

At least 37 records · Page 2Linked to original sources
PubMed1993

Bilirubin inhibits protein kinase C activity and protein kinase C-mediated phosphorylation of endogenous substrates in human skin fibroblasts.

The primary target and molecular basis of bilirubin toxicity to cellular function are not known. We have studied the effect of bilirubin on protein kinase C activity in subcellular fractions of human skin fibroblasts and on protein kinase C-mediated phosphorylation of endogenous substrates. Bilirubin inhibited the kinase activity in a concentration-dependent manner: a 50% inhibition was achieved by 45 mumol/l in the homogenate and 75 mumol/l in both the cytosolic and membranous fractions. Inhibition of protein kinase C activity by bilirubin was reversed by increasing the concentrations of activating lipids in both the cytosolic and membranous fractions. Bilirubin-induced inhibition of phosphorylation of endogenous proteins, in both fractions, was noted in the presence of calcium and the activating lipids, but not in the absence of the activators. This inhibition may play a role in the pathogenesis of bilirubin toxicity.

Bilirubin↗
PubMed1993

Mathematical textbook of deformable neuroanatomies.

Mathematical techniques are presented for the transformation of digital anatomical textbooks from the ideal to the individual, allowing for the representation of the variabilities manifest in normal human anatomies. The ideal textbook is constructed on a fixed coordinate system to contain all of the information currently available about the physical properties of neuroanatomies. This information is obtained via sensor probes such as magnetic resonance, as well as computed axial and emission tomography, along with symbolic information such as white- and gray-matter tracts, nuclei, etc. Human variability associated with individuals is accommodated by defining probabilistic transformations on the textbook coordinate system, the transformations forming mathematical translation groups of high dimension. The ideal is applied to the individual patient by finding the transformation which is consistent with physical properties of deformable elastic solids and which brings the coordinate system of the textbook to that of the patient. Registration, segmentation, and fusion all result automatically because the textbook carries symbolic values as well as multisensor features.

Algorithms↗
PubMed1993

Age-dependent sensitivity of cultured rat glial cells to bilirubin toxicity.

The results of studies conducted in neural tissues and neuronal cell lines suggest that bilirubin is toxic to various cellular functions. Using stable bilirubin solutions and primary cultures of fetal rat glial cells we report on the toxic effects of bilirubin on cell morphology, cell viability, and mitochondrial function. Glial cells in culture exhibit age-in-culture-dependent sensitivity to bilirubin toxic effects. Between the ages of 2 and 12 days in vitro, a gradual tolerance to bilirubin developed. Bilirubin exposure resulted in 55, 22, and 5% decreases in mitochondrial function in 4-, 8-, and 12-day-old cells in culture, respectively. In addition, bilirubin toxicity was dependent on bilirubin-albumin molar ratio and bilirubin concentration and only partially dependent on length of exposure. The age-dependent phenomenon raises concern regarding the potential toxicity associated with exposure of premature neural cells to bilirubin.

Animals↗
PubMed1993

Children's sleep under the threat of attack by ballistic missiles.

The present paper reports on the influence of the Scud missile attacks during the Gulf War on the sleep of Israeli children. Two studies were performed. In the first, sleep habits and sleep disturbances of 61 (mean age 20 months) infants were assessed by questionnaires completed by their parents 5 months before the war and immediately after the end of the War. Comparison of pre- and post-war data revealed no major changes in sleep habits or in sleep quality. In the second study, sleep of 55 children was monitored at home by actigraphs during the last month of the War. All children were aroused during missile attacks, but returned to sleep immediately, with no evidence of carry-over effects once the 'all clear' sign was given. Comparison of sleep quality measures obtained during the War with those of age- and sex-matched children monitored a year before the war did not reveal any significant differences apart from the immediate response to the attack.

Journal Article↗
PubMed1993

Effect of skinfold thickness on transcutaneous bilirubin measurements.

We studied the effect of skinfold thickness on the correlation between serum total bilirubin level and transcutaneous bilirubin (TcB) readings. Skinfold thickness measurements were taken at 1-4 h of age. Serum total bilirubin levels and TcB readings were obtained at 1-4 (first) and 44-56 h of age (discharge). No correlation was found between first reading and skinfold thickness (rho = -0.196), whereas correlations with first serum bilirubin level and blood hematocrit were 0.397 and -0.373, respectively. The correlation between discharge serum total bilirubin level and TcB reading was affected by skinfold thickness, and not improved with the use of first reading as a reference for discharge reading.

Bilirubin↗
PubMed1993

Standards of skinfold thickness and anthropometric indices in term Israeli newborn infants.

Anthropometric measurements including weight, length, head and mid-arm circumferences, skinfold thickness (biceps, triceps, subscapular, abdominal, suprailiac and quadriceps) were obtained from 250 singleton, full-term infants within 4 h of birth. Anthropometric indices for total body fat stores such as arm fat and nonfat areas, adiposity and ponderal indices, and weight/length ratio were calculated. These data may be helpful in determining nutritional status at birth and assessing postnatal growth of Israeli infants.

Anthropometry↗
PubMed1992

Neonatal jaundice and bilirubin encephalopathy: a clinical and experimental reappraisal.

Hyperbilirubinemia and bilirubin encephalopathy are well-known occurrences in the neonatal period. The fact that bilirubin might be toxic to neural cells stems from the neurological picture that has emerged and the associated hyperbilirubinemia. Studies of the relationship between hyperbilirubinemia in healthy full-term infants and the long-term consequences showed little or no effect of bilirubin. Nevertheless, bilirubin is still considered toxic to premature infants and infants with hemolysis. In addition, in spite of a fairly detailed understanding of the chemistry of bilirubin and the biochemistry of bilirubin metabolism, the primary target of its toxic effect is still not known. The difficulties in analyzing the results are due to the variation in experimental designs, the use of different animal models and cell systems and the use of unstable bilirubin solutions. We review some of the problems related to clinical and experimental studies of bilirubin toxicity.

Animals↗
PubMed1991

Intravenous immunoglobulin for Flavobacterium-induced thrombocytopenia in a premature infant.

Gram-negative septicemia at times causes morbidity and mortality in newborn nurseries. Prophylactic intravenous immunoglobulin results in a significant decrease in incidence and severity of septicemia resulting from infection in infants. The present case report describes the successful use of high-dose intravenous immunoglobulin in a Flavobacterium-induced thrombocytopenia in a premature infant.

Bacterial Infections↗
PubMed1991

Successful replantation of both legs in a child--5-year followup: case report.

Replantation of lower extremities is an infrequent procedure, and is rarely indicated, due to the usual severity of the primary injury plus the possibility of good prosthetic substitution. We report a case of successful replantation of both legs in an 8-year-old boy (despite Aspergillus flavus septicemia) with followup of 5 years. This case suggests that leg replantation should be considered in young patients. This appears to be the second reported case of successful replantation of both legs.

Adolescent↗
PubMed1990

Bilirubin-neural cell interaction: characterization of initial cell surface binding leading to toxicity in the neuroblastoma cell line N-115.

The toxicity of bilirubin to the nervous system might be due to its effect on several key enzyme reactions occurring in the intracellular compartment as suggested by in vitro studies. The question of how bilirubin, a molecule with poor solubility in water and organic solvents, interacts with the plasma membrane and reaches intracellular targets is unclear. In an attempt to get some insight into this problem, we have measured the uptake of bilirubin from bilirubin-albumin solutions by the murine neuroblastoma cell line N-115. At a constant total concentration of bilirubin, the initial rate, as well as the extent of uptake, increases with increasing bilirubin to albumin molar ratio (B/A). The binding is reversible, at least partially, as indicated by the ability of albumin to extract cell-bound bilirubin. The cellular uptake of bilirubin was found to depend also on the concentration of bilirubin, on temperature and on pH. The results are not consistent with either a carrier-mediated transport or passive diffusion across the plasma membrane. The data, however, seem to fit a multistep binding of bilirubin to the plasma membrane proposed for the interaction of bilirubin with synaptosomal plasma membrane vesicles, erythrocyte ghosts and lipid vesicles. These studies, thus, reveal the complexity of the binding interaction at the level of the plasma membrane and leave open the question of transport across the membrane.

Albumins↗
PubMed1990

Massive bone allograft: a salvage procedure for complex bone loss due to high-velocity missiles--a long-term follow-up.

The treatment of high-velocity missile injury to the limbs is often associated with segmental bone loss, as well as damage to neurovascular and soft tissue. In such "limb threatening" cases, massive bone allograft can fill the bone defect and offer stability to the soft tissue reconstruction. The return of function in the affected limb is relatively rapid when using this method as a primary procedure. The indications for use of this technique and illustrative case reports are presented and discussed.

Adult↗
PubMed1989

Bilirubin toxicity in a neuroblastoma cell line N-115: I. Effects on Na+K+ ATPase, [3H]-thymidine uptake, L-[35S]-methionine incorporation, and mitochondrial function.

Though bilirubin is reported to affect a variety of cellular functions, the primary target of its toxic effect is still not known. A major problem in understanding this is the wide variation in results reported by different groups. This is probably due to the differences in stability of bilirubin solutions arising from large differences in bilirubin:albumin molar ratios used in experiments. Hence in studying the toxic effects of bilirubin in tissue culture systems, it is important to be certain that the bilirubin is maintained in solution throughout the time of the exposure to bilirubin. Spectrophotometric measurements have shown that bilirubin is stable in Dulbecco's modified Eagle medium solution at bilirubin:albumin molar ratios up to 3. Under these defined conditions, bilirubin was found to affect Na+K+ ATPase, [3H]-thymidine uptake, L-[35S]methionine incorporation into protein and mitochondrial function at bilirubin concentrations up to 125 microM and bilirubin:albumin molar ratio of 1.5. Toxic effects on all parameters measured were evident at bilirubin:albumin molar ratio of 1.5 after a minimum of 2 h of exposure. No effect was evident at a bilirubin:albumin molar ratio below 1. Although it is not possible to identify with certainty the primary target, the effect on mitochondrial function appeared earlier and was more profound than that seen with the other assessed functions.

Albumins↗
PubMed1989

Bilirubin toxicity in a neuroblastoma cell line N-115: II. Delayed effects and recovery.

Clinical studies have suggested that the early stages of bilirubin encephalopathy are reversible. These phenomena are investigated at the cellular level using the neuroblastoma cell line N-115 as a model system. To determine whether the cell line N-115 can recover from bilirubin toxicity, and whether the cellular function remains intact after a short period of bilirubin exposure during which time no toxic effects are manifest, the cells are exposed to bilirubin at varying concentrations and varying bilirubin:albumin ratios for 1 and 2 h. The bilirubin is then washed out, and the cells are reincubated in fresh media with appropriate amounts of albumin. Mitochondrial function, [3H]thymidine uptake and L-[35S]methionine uptake are assessed at 2, 8, and 24 h of reincubation after the bilirubin washout. After the short-term exposure, the cells begin to demonstrate evidence of toxicity in all parameters measured 8-24 h after the bilirubin washout. After the 2-h exposure to bilirubin, the cells demonstrate significant toxicity within 2 h of the bilirubin washout. The degree of toxicity seems to depend on the bilirubin:albumin ratio and bilirubin concentration. In general, after bilirubin exposure of 1 h or longer, the N-115 cells develop evidence of toxicity which is progressive and irreversible.

Albumins↗
PubMed1989

[Early microsurgical reconstruction of extremities with free microvascular flaps].

The key to successful reconstruction of the extremities after complex trauma is often adequate soft tissue cover of the injured area. In the past, when surgical debridement of wounds was too extensive, or it exposed vital structures such as blood vessels, nerves, tendons or bones, the limb either had to be amputated or reconstructed in multiple surgical procedures. The use of free microvascular flaps in the immediate postinjury period allows single stage reconstruction of wounds including exposed vital tissues. It promotes limb salvage and shortens recovery time after severe trauma. 4 patients with severe complex trauma of the extremities underwent reconstruction with immediate free microvascular flaps, which included latissimus dorsi and rectus abdominis muscle and free scapular flaps. The surgical protocol included debridement of wounds on arrival with primary fixation of fractures and additional debridement procedures in the first week until the wound was stable. Then final fixation of fractures was performed and the wound was covered by a free microvascular flap. With this technique, single stage reconstruction is possible in most cases, with improvement in function and cosmetic outcome, multiple operations are avoided and the recovery period is shortened.

Adult↗
PubMed1988

Sonographic detection of occult bone fractures.

Two infants of 24 and 20 months of age with painful local swelling at the femoral and clavicular regions were investigated by ultrasound after a negative radiographic study of the adjacent bones. In both children high resolution ultrasound clearly revealed the presence of bone fractures in addition to the soft tissue hematomas. These fractures were confirmed by a repeat radiographs performed 6 and 8 days later. Although sonography is not the method of choice for the detection of bone fractures, it may be worthwhile to examine the bone contour for a fracture when a painful swelling adjacent to bone is present. The method may be particularly rewarding in children due to its rapid non-invasive nature and to the small tissue thickness that has to be penetrated.

Child, Preschool↗
PubMed1985

Isolated anterior inguinal dislocation of the hip joint.

Anterior dislocation of the hip joint is rare, accompanied usually by a fracture of adjacent bony structures. A case of isolated anterior inguinal dislocation of the hip joint is hereby presented with 22 months of followup. The mechanism of this rare injury is usually forcible abduction and extension of the hip joint. Early diagnosis and reduction, with immediate post-reduction roentgenograms to discover any fragments in the joint space, should be done. In this patient, X-rays 11 and 22 months after reduction appeared normal.

Aged↗