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Biomedical subjects

D Talwar

Publications and source records attributed to D Talwar.

At least 37 records · Page 2Linked to original sources
PubMed1990

Neuroblastoma in a patient with Sotos' syndrome.

Sotos' syndrome, or cerebral gigantism, is a disorder of growth regulation. Tumours have occasionally been reported in children with Sotos' syndrome, but it is uncertain whether this is a coincidence, or whether it is aetiologically related to the underlying disorder of growth. We report a 15 month old child with a paraspinal neuroblastoma and Sotos' syndrome and suggest that children with this condition may be at higher risk for developing tumours than the general population.

Facial Bones↗
PubMed1990

Endometrial response to deciduogenic stimulus in ovariectomized rhesus monkeys treated with oestrogen and progesterone: an ultrastructural study.

The present work continues our aim of establishing an experimental model to study the decidual cell reaction to an artificial deciduogenic stimulus in the long-term ovariectomized rhesus monkey treated with oestrogen followed by progesterone. The fine structural details of decidual, granular and plaque cells, which constituted the endometrial cellular response to the deciduogenic stimulation in the present study, revealed striking similarities with those reportedly present in an endometrial response to blastocyst implantation in the rhesus monkey. Plaque epithelia showed a significant degree of hypertrophy, hyperplasia and differentiation followed by a steady degeneration by day 32 (equivalent to day 16 after trauma) of treatment. The plaque cells were shown to contain numerous regular-shaped mitochondria, polyribosomes and large amounts of rough endoplasmic reticulum (RER) in their cytoplasm and were characteristically arranged in clusters or acini formation surrounded by discrete basal laminae. As early as day 28 of treatment, the initiation of stromal decidual cell transformation was noted and, by day 48, a sizeable pool of decidual cells was found. The decidual cells had rounded nuclei and elaborate arrangements of interconnected cisternae of RER which were often moderately dilated and filled with amorphous, electron-dense material. Granular cells were characterized by eccentrically located nuclei and numerous membrane-bound, electron-dense granules in their cytoplasm and were found in increasing numbers in the stroma around decidual cells, blood vessels and glandular epithelia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

CAMFAK syndrome: a demyelinating inherited disease similar to Cockayne syndrome.

CAMFAK syndrome is an inherited disease characterized by congenital cataracts, microcephaly, failure to thrive, and kyphoscoliosis with onset in early infancy. Its pathogenesis has not been clearly defined. We report on a patient with this syndrome and present evidence that it is a neurologic disease characterized by peripheral and central demyelination similar to that seen in Cockayne syndrome.

Abnormalities, Multiple↗
PubMed1989

Is there any delta 5-3 beta hydroxysteroid dehydrogenase activity in preimplantation embryo of rhesus monkey?

This is the first report on the histochemical assessment of delta 5-3 beta hydroxysteroid dehydrogenase activity in all the preimplantation embryonic stages in the rhesus monkey (Macaca mulatta). An apparent stage dependent increase in enzyme activity was obtained, however, distinctively a high degree of non-specificity in enzyme reaction was noted primarily in morulae and blastocysts. Such marked non-specificity in the histochemical enzyme reaction for delta 5-3 beta hydroxysteroid dehydrogenase activity was not found in mouse blastocysts. High amounts of endogenous steroids present within rhesus embryos, or the participation of non-specific dehydrogenases could account for the observed non-specificity. Furthermore, the present report documents the pattern and degree of association (r = 0.9; P less than 0.01) between developmental stage and gestational age of preimplantation rhesus embryos, and thus provides a normal in situ cell cleavage rate of preimplantation embryo in the rhesus monkey.

3-Hydroxysteroid Dehydrogenases↗
PubMed1988

Endometrial phosphatases, beta-glucuronidase and cathepsin D during menstrual cycle and pre-implantation stages of gestation in the rhesus monkey (Macaca mulatta).

beta-glucuronidase, cathepsin D, acid and alkaline phosphatases were studied in rhesus monkey endometrium during the menstrual cycle (day -6 to day +10) and pre-implantation stages (day +3 to day +6) of gestation, with day 0 considered as the day of ovulation. Acid hydrolases exhibited low levels in proliferative phase endometria followed by their gradual rise in the secretory phase of the menstrual cycle. Despite no shifts in the levels of serum progesterone and estradiol-17 beta, the pre-implantation period was, however, associated with distinct changes in enzyme profiles characterized by lower absolute levels (P less than 0.05) of acid phosphatase and beta-glucuronidase on days 3 to 6 of gestation, whereas cathepsin D activity declined significantly (P less than 0.05) on days 5 and 6. Alkaline phosphatase showed a characteristic rise during the pre-ovulatory period with a gradual lowering of its level in post-ovulatory phase endometria of a non-fertile cycle; in contrast, during early gestation, alkaline phosphatase activity showed a marked elevation (P less than 0.05) on days 5 and 6 of gestation. The significance of these findings is discussed.

Acid Phosphatase↗
PubMed1988

Fetal glycaemic control and neonatal complications in diabetic pregnancy.

To examine the relationship between fetal glycaemic control and macrosomia or neonatal hypoglycaemia, we measured umbilical cord glycosylated haemoglobin (GHb) by affinity chromatography in 44 diabetic and 40 normal pregnancies. Levels of GHb in cord blood were not significantly different between these two groups, suggesting good maternal glycaemic control was achieved in the diabetic patients. Moreover in the diabetic pregnancies, cord GHb levels did not differ in infants who were macrosomic or developed hypoglycaemia by comparison with those infants who showed neither phenomenon. We conclude that overall fetal glycaemic control in the 4-6 week period prior to delivery does not appear to influence these common neonatal complications of diabetic pregnancy.

Adult↗
PubMed1987

The relative extent of glycation of haemoglobin and albumin.

The level of non-enzymatic glycation of a protein is thought to depend on the number of sites available for reaction, the half-life of the protein and the ambient concentration of glucose. Accordingly, the modification of two blood proteins with a similar number of potential sites but different survival times was examined in non-diabetic patients by periodate oxidation and by reduction with [3H]borohydride. The amount of glycation of haemoglobin and its sub-fractions HbA1 and HbA1c were determined to be 0.44, 2.42 and 2.24 mol/mol respectively and the corresponding value for albumin was 0.37 mol/mol protein. Amino acid analysis showed that the epsilon amino groups of albumin were more extensively modified than they were in haemoglobin and thus it is concluded that the average rate of reaction of the lysine residues in albumin is markedly faster than in haemoglobin.

Amino Acids↗
PubMed1987

Benzodiazepine receptor development in murine glial cultures.

Benzodiazepine (BDZ) receptor binding characteristics were determined from glial cultures prepared from the cerebral hemispheres of newborn mice. Receptor binding and saturation analyses were performed at various ages in culture on intact cells. Utilizing 5 nM 3H-diazepam at 0.4 degrees C, specific binding reached a plateau at 16-21 days after plating. A single high-affinity binding site was identified with Kd 25.3 +/- 2.6 nM and Bmax 7,575 +/- 410 fmol/mg protein. Inhibition studies utilizing clonazepam indicated that this ligand, thought to have affinity exclusively for neurons, displaces more than 20% of the specific BDZ binding at concentrations as low as 300 nM, although the IC50 was 1.5-2.0 microM. In contrast, the IC50 for Ro5-4864 was 10-20 nM.

Animals↗
PubMed1987

Peroxisomal disorders. A review of a recently recognized group of clinical entities.

The peroxisome is a small organelle present in almost all cells. The peroxisomal disorders are a newly recognized group of disease entities that share structural and/or functional abnormalities of the peroxisomes, are inherited, and may have profound neurologic and systemic effects. Some of the disorders lack peroxisomes in cells, while others have single or multiple peroxisomal enzymatic deficiencies despite the presence of normally appearing peroxisomes. The prototype of the peroxisomal disorders is Zellweger syndrome. X-linked adrenoleukodystrophy, neonatal adrenoleukodystrophy, infantile Refsum disease, hyperpipecolic acidemia and Refsum disease are some of the other disease entities presently classified as peroxisomal disorders. Accurate methods of pre- and postnatal diagnosis are available. Treatment strategies are being developed, but at this time prenatal diagnosis and appropriate genetic counseling is the best therapeutic intervention for those peroxisomal disorders characterized by profound neurologic handicap and early death.

Adrenoleukodystrophy↗
PubMed1985

Glycosylated albumin and glycosylated proteins: rapidly changing indices of glycaemia in diabetic pregnancy.

Serial measurements of glycosylated albumin (GAlb), glycosylated plasma proteins (GPP) and glycosylated haemoglobin (GHb) were performed by affinity chromatography throughout the course of pregnancy in 14 insulin-dependent diabetic women. In patients whose glycaemic control improved markedly during pregnancy, the concentrations of GAlb and GPP decreased by more than 50 per cent after four weeks of good diabetic control. By contrast, the rate of decrease in GHb levels in the same patients was significantly less and did not indicate a comparable improvement in glycaemia until 12 weeks after good diabetic control was established. Elevated concentrations of GAlb or GPP decrease much more rapidly than GHb concentration when diabetic control is improved; thus measurement of glycosylated proteins is a valuable adjunct to serial blood glucose monitoring in clinical circumstances such as diabetic pregnancy, where early confirmation of good diabetic control is important.

Adult↗
PubMed1983

Determination of glycosylated adult and foetal haemoglobins by affinity chromatography.

Estimation of adult glycosylated haemoglobin by affinity chromatography was found to be quick and less dependent on ionic strength, pH and temperature than ion-exchange chromatography. Results obtained by both procedures correlated strongly (r = 0.96) but the range for normal subjects was smaller with the affinity assay. The affinity method correlated equally well with the colorimetric assay (r = 0.95). However, the method did not measure all the glycosylated forms, and only half of the glycosylated species isolated by ion-exchange chromatography was bound to the affinity resin. It also showed that the amount of glycosylated haemoglobin in cord blood is less than in adult blood.

Aging↗
PubMedDate not supplied

Continuous electrophysiologic monitoring of cerebral function in the pediatric intensive care unit.

The brains of children admitted to intensive care units are at considerable risk. Electrophysiologic techniques are the most suitable of available methods for uninterrupted surveillance of brain function. Although the use of routine electroencephalography for this purpose is impractical, automated electroencephalographic signal analysis and application of digital computer technology have made continuous monitoring of cerebral function feasible. Various methods of displaying modified electroencephalographic data in an understandable and interpretable form have been developed; the most commonly used devices are the cerebral function monitor and the compressed spectral array. Practical clinical applications and limitations of continuous cerebral function monitoring are discussed.

Brain↗
PubMedDate not supplied

Mechanisms of antiepileptic drug action.

Animal seizure models, in vitro preparations of cell cultures and tissue slices, and an unravelling of some of the basic mechanisms underlying epileptogenesis and epilepsy have furthered the understanding of mechanisms of action of antiepileptic drugs at the cellular and subcellular levels. Nevertheless, the mechanism of action of most antiepileptic drugs in clinical use is incompletely understood. Multiple physiologic mechanisms are altered by antiepileptic drugs. Some of these drugs, such as phenytoin and carbamazepine, decrease sustained repetitive firing and post-tetanic potentiation through their blocking effects on the sodium channel. Benzodiazepines and barbiturates enhance GABA-mediated inhibition. Many antiepileptic drugs inhibit calcium influx and calcium-mediated secondary effects at supratherapeutic concentrations. Newer drugs that inhibit excitatory receptors or enhance various forms of inhibition are presently under investigation.

Action Potentials↗
PubMedDate not supplied

Megalencephaly secondary to occlusion and stenosis of sigmoid sinuses.

Bilateral, idiopathic, essentially asymptomatic but hemodynamically significant stenosis or occlusion of the sigmoid sinuses is extremely rare. We report a child with the angiographic features of occlusion of the right sigmoid sinus and severe stenosis on the contralateral side, presenting with megalencephaly and a cranial bruit. Cranial computed tomographic scans demonstrated increased subarachnoid spaces and borderline ventricular enlargement.

Arterial Occlusive Diseases↗
PubMedDate not supplied

EEG correlation of improvement in hemolytic-uremic syndrome after plasma infusion.

We report a previously undescribed electroencephalographic pattern of epochs of diffuse delta background (85-240 sec) alternating with epochs of classic "burst suppression" (90-270 sec) in a 13-month-old girl with hemolytic-uremic syndrome. A dramatic electroencephalographic improvement was evident on continuous monitoring of cerebral function 3 hours after initiating fresh frozen plasma infusion, well before any clinical improvement was apparent. This patient, in addition to the unusual electroencephalographic findings, illustrates the role of continuous electrophysiologic monitoring of cerebral function and supports the use of fresh frozen plasma in hemolytic-uremic syndrome.

Cerebral Cortex↗
PubMedDate not supplied

Nonepileptic events in normal and neurologically handicapped children: a video-EEG study.

Nonepileptic episodic phenomena are reported in 27 of 124 children (21.8%) who had video-electroencephalographic studies performed. Mean age was 7.4 years (S.D.: 6.0; range: 0.1-19). Nineteen (70%) were neurologically impaired (Group 1) and 8 (30%) neurologically normal (Group 2). The final diagnoses included movement sequences (48%), conversion disorder (22%), behavioral staring (18%), sleep disorder (11%), behavioral episodes (8%), and central apnea (8%). In Group 1, abnormal movements (58%) and staring (26%) were most common; conversion disorder (62.5%) was most common in Group 2. Unnecessary medication therapy was prevented in many children. Video-electroencephalography is valuable in preventing over-medication and misdiagnosis.

Adolescent↗
PubMedDate not supplied

Factors influencing serum levels of carbamazepine and carbamazepine-10,11-epoxide in children.

Carbamazepine-10,11-epoxide (CBZ-E), the principal metabolite of carbamazepine (CBZ), is reported to have antiepileptic and toxic effects similar to CBZ. Steady-state CBZ and CBZ-E levels (high performance liquid chromatography, HPLC assay) were reviewed in 225 outpatient children and young adults taking CBZ with or without other antiepileptic drugs (AEDs). In patients on CBZ alone, mean serum concentration of CBZ was 7.9 +/- 1.9 micrograms/ml and of CBZ-E was 1.5 +/- 0.6 micrograms/ml. The CBZ-E/CBZ ratio was 19.6 +/- 2.4%. Serum CBZ increased with increasing age and with CBZ dose. CBZ-E increased with increasing CBZ dose but was unaffected by age. The CBZ-E/CBZ ratio progressively declined with age. Co-medication with barbiturates or valproic acid significantly increased CBZ-E. Phenytoin showed a similar trend while ethosuximide caused the least change. Patients on CBZ and two or more other AEDs had highest CBZ-E levels and CBZ-E/CBZ ratio. CBZ and CBZ-E levels are variably affected by age, CBZ dose, and co-medication with other AEDs. When other AEDs are administered, careful monitoring is especially indicated in order to avoid toxicity.

Adolescent↗