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Biomedical subjects

I Weiss

Publications and source records attributed to I Weiss.

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

Molecular basis for alpha-thalassemia associated with the structural mutant hemoglobin Suan-Dok (alpha 2 109leu----arg)

Hemoglobin (Hb) Suan-Dok (alpha 109Arg) is a rare alpha-globin structural mutation that is linked to an alpha-thalassemia (alpha-thal) determinant. When inherited in trans to an alpha-thal-1 mutation (-), it results in Hb H disease associated with low levels (9%) of the Suan-Dok Hb. The nature of the thalassemic defect associated with the alpha SD mutation has been investigated by structural and functional studies. Sequence analysis of the cloned Suan-Dok allele showed a missense mutation (T----G) at codon 109 in an otherwise normal alpha 2-globin gene. When the alpha 2SD-globin gene was introduced into mouse erythroleukemia cells, the steady state alpha-globin messenger RNA (mRNA) level was equivalent to the alpha A-globin gene control. Although in vitro translation of a synthetic alpha 2SD-globin mRNA generated levels of alpha globin equivalent to alpha 2A-globin mRNA at early time points, the ratio of alpha SD to alpha A globin decreased markedly at later time points. These data suggest that the thalassemic defect associated with the Suan-Dok mutation results from a significant instability of the alpha SD globin.

Amino Acid Sequence↗
PubMed1990

Inactivation of human alpha-globin gene expression by a de novo deletion located upstream of the alpha-globin gene cluster.

Synthesis of normal human hemoglobin A, alpha 2 beta 2, is based upon balanced expression of genes in the alpha-globin gene cluster on chromosome 16 and the beta-globin gene cluster on chromosome 11. Full levels of erythroid-specific activation of the beta-globin cluster depend on sequences located at a considerable distance 5' to the beta-globin gene, referred to as the locus-activating or dominant control region. The existence of an analogous element(s) upstream of the alpha-globin cluster has been suggested from observations on naturally occurring deletions and experimental studies. We have identified an individual with alpha-thalassemia in whom structurally normal alpha-globin genes have been inactivated in cis by a discrete de novo 35-kilobase deletion located approximately 30 kilobases 5' from the alpha-globin gene cluster. We conclude that this deletion inactivates expression of the alpha-globin genes by removing one or more of the previously identified upstream regulatory sequences that are critical to expression of the alpha-globin genes.

Adult↗
PubMed1989

Disturbances of brain maturation and neurodevelopment during chronic renal failure in infancy.

Fifteen infants with moderate to severe congenital renal disease were prospectively studied by serial renal, neurodevelopmental, neurophysiologic, and anthropometric assessments. The observation period ranged from 3 to 25 months (mean = 10.9). Eight patients maintained a Mental Development Index (MDI) above the 16th percentile (greater than -1 SD) and comprised group 1. Of the remaining seven patients (group 2), three had an MDI less than 16th percentile when first studied and four had serial decreases of the MDI to less than 16th percentile. Although motor development was more delayed in group 2 at study entry, there were no significant changes of motor performance levels for either group during the study period. Group 2 patients had smaller length (p less than 0.05) and head circumference (p less than 0.05) standard deviation scores in comparison with group 1, and they had higher serum creatinine values (mean = 3.8 vs 1.3 mg/dl, respectively; p less than 0.01). By spectral electroencephalography, the expected progressive increase of the frequency of cerebral cortical background activity with age was demonstrated in group 1 but was not seen in group 2 (multivariate analysis of variance p less than 0.03). This increase of faster-frequency activity was primarily manifested in the left cerebral hemisphere of group 1 patients (p less than 0.01), a finding that was also absent in group 2. The frequent occurrence of neurodevelopmental abnormalities in infants with renal failure is possibly a consequence of impaired dominant hemispheric maturation in the first several years of life, which is clinically manifested as deterioration of cognitive function.

Cephalometry↗
PubMed1988

Granular cell myoblastoma of the parapharyngeal space.

A granular cell myoblastoma of the parapharyngeal space is presented. Although uncommon, this neoplasm of controversial origin must be considered in the differential diagnosis of all nonenhancing parapharyngeal space masses.

Adolescent↗
PubMed1987

Unexpectedly long 14S ribosomal RNA gene in Tetrahymena mitochondria.

Extraction of RNA from Tetrahymena mitochondrial ribosomes yields several RNA species, including a "large" 21S molecule, a "small" 14S molecule, a 7S molecule, and other smaller RNAs. The molecular weight of the 14S rRNA indicates that it is about 1,300 bases in length. We have sequenced the 14S rRNA gene and, by aligning our sequence with that of the corresponding small rRNA from E. coli, find that the 14S rDNA is at least 1,635 bases in length. We propose, based on the results of hybridization studies, that this unexpected length is due to the presence of 7S RNA sequence within the 14S gene sequence. The 7S region is apparently lost from the 14S rRNA, yet is still a component of the ribosome.

Animals↗
PubMed1986

[In vitro and in vivo effect of gold thioglucose on the insulin- and glucagon-secretion of the isolated perfused rat pancreas].

Effects of gold thioglucose on the insulin and glucagon secretion by the isolated perfused pancreas of Wistar rats in vivo and in vitro Gold thioglucose (GTG), hitherto administered predominantly to mice can also be used in rats in a non toxic dosage, if GTG is injected intravenously (i.v.) together with sodium hexobarbital. Wistar rats tolerate a single injection of GTG in doses ranging from 40 to 1200 mg/kg bw. GTG (10 mmol/l in the perfusion medium) has no in vitro effect--tested by the isolated perfused rat pancreas--on the basal (5.5 mmol/l glucose) or stimulated (11 mmol/l glucose) insulin (IRI)-secretion. This is valid also for glucagon (IRG)-secretion. After in vivo injection of GTG (600 mg/kg bw, together with sodium hexobarbital (10 mg/100 g bw, i.v.] extensive alterations of IRI- and IRG-secretion result as tested under in vitro conditions in the isolated perfused pancreas of the rat, Glucose stimulation (11 mmol/l) causes a hyperinsulinism and a hypersecretion of IRG, a so-called paradoxical glucagon secretion, lasting for 2 days while IRI secretion is already diminished. At the same time food intake is very low and the body weight decreases. Ten days later the body weight has reached the starting value again and the IRI secretion shows again signs of hyperinsulinism. Six months after a single injection of GTG (600 mg/kg bw, i.v.) the rats were obese and react after glucose stimulation with hyperinsulinism and again with a paradoxical glucagon secretion. The blood glucose levels were normoglycaemic, whereas serum IRI rose in parallel with development of the obesity. Also with histological methods we could distinguish an acute from a chronic phase of GTG toxicity visible in the tested organs (liver, kidney, thyroid gland). The endocrine pancreas reacts after a single injection of GTG with a lowered number of B cells. The remaining cells reveal variable amounts of degranulation. In the early phase the hypothalamus, in particular the ventromedial hypothalamic nucleus, shows most clearly signs of destruction and 6 months after a single injection of GTG the number of cells is still reduced in this region. We conclude that GTG reacts primarily on the hypothalamus and modulates the reactivity of the endocrine pancreas in a permanent manner via the vegetative nervous system, because we test the function of the pancreas in an in vitro system. As a consequence the threshold of the B and A cell against the stimulus glucose is altered in two ways.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

A double blind study of vitamin B6 in Down's syndrome infants. Part 2--Cortical auditory evoked potentials.

Cortical auditory evoked potentials (CAEPs) were recorded at 1 and at 3 years of age in 19 children with Down's syndrome participating in a double blind trial of vitamin B6 and placebo begun in early infancy and continued for 3 years. CAEPs have previously been shown to have abnormally high amplitude in Down's syndrome patients. The CAEPs of the patients in the B6-treated and placebo groups were compared. Only minor effects were found in the CAEPs recorded at 1 year of age. At 3 years of age, however, comparison of the B6-treated group and the placebo group revealed significant differences in both amplitudes and latencies of CAEP components. Peak to peak amplitudes of prominent components were significantly lower in B6-treated patients than in their placebo controls. Amplitude correlated in some cases with whole blood serotonin levels. Latencies for several prominent evoked peaks were significantly longer in B6-treated patients.

Child, Preschool↗
PubMed1985

[Effect of subtotal small intestine resection on insulin and glucagon secretion by the isolated perfused rat pancreas following glucose stimulation].

An attempt has been made to investigate possible regulatory effects of gastrointestinal hormones on insulin and glucagon secretion in Wistar rats that had been subjected to partial resection of the duodenum and jejunum or the ileum. Release of insulin and glucagon was studied on perfused pancrease 4 weeks after the operation. Partial resection of both the duodenum and jejunum resulted in a significant decrease of glucose-induced insulin secretion and basal glucagon release when compared with the controls. Glucagon release was not further suppressed by increasing glucose concentration in the perfusion medium. Resection of the ileum only had no effects. Also, there was no difference to be observed in plasma insulin levels between the two groups. Resection of the ileum, however, provoked a drastical decrease of plasma insulin levels. Food intake was not significantly changed while body weight slightly decreased 1 week after operation but returned to normal after 4 weeks. The results suggest that the various parts of the small intestine seem to be involved in the regulation of glucose-stimulated insulin secretion as well as basal glucagon release. The alterations in glucose-stimulated insulin or glucose-suppressed glucagon secretion are likely due to the action of gastrointestinal hormones or hitherto unknown peptides.

Animals↗
PubMed1985

[Hyperchlorhydria of the stomach following hypothalamus lesions in the rat].

Effects of ventromedial hypothalamic (VMH corresponding Nucleus ventromedialis hypothalami NVM) lesion on gastric acid output were examined. Acid output was determined by using the gastric perfusion method in rats anesthetized with urethan. With lesion of the ventromedial hypothalamus a significant increase in acid output occurred 28 days after lesion. Basal acid output increased from 5.9 +/- 2.5 to 32.2 mumol H+ X h-1 and stimulated acid output increased from 15.4 +/- 7.2 to 75.3 +/- 15.3 mumol H+ X h-1. Gastric hypersecretion in rats with VMH lesions was due to a vagally-mediated gastric stimulation. This model is useful to trial drugs which reduce gastric acidity.

Animals↗
PubMed1984

Influence of methimazole on murine thyroiditis. Evidence for immunosuppression in vivo.

Thionamide drugs are immunosuppressives in vitro. To examine this action in vivo, A/J mice were immunized with human thyroglobulin (hTg) (0.5 mg intraperitoneal injections for 5 d) beginning on days 6, 24, and 43 with or without methimazole (M) (0.05%) and l-thyroxine (T4) (0.1 micrograms/ml to prevent thyroid hypertrophy) in their water supply. Groups (n = 8) were killed on days 37, 42, and 59. Spontaneous splenic IgG-secreting cells determined by Staphylococcus protein A-linked sheep erythrocytes (SRBC) via indirect plaque-forming cell (PFC) assay indicated polyclonal stimulation induced by the hTg exposure (controls = 2,285 +/- 599, hTg-only = 5,570 +/- 470 PFC per 10(6) spleen cells), but this was significantly reduced in the M plus T4-treated group (3,640 +/- 415 PFC, P = 0.05). hTg antibody was measured by specific PFC assay using hTg-linked SRBC. Anti-hTg PFC were absent in controls and were 147 +/- 41, 25 +/- 8, and 173 +/- 58 PFC per 10(6) spleen cells in the hTg-only groups on days 37, 42, and 59, respectively. Anti-hTg PFC results in the M plus T4-treated animals were significantly reduced to 0, 15 +/- 5, and 63 +/- 30 anti-hTg PFC. Histological examination revealed a marked thyroiditis in hTg-only animals and a significantly reduced degree of mononuclear cell infiltration and follicular destruction in the M plus T4-treated groups (graded 1.9 compared with 3.6 in hTg-only P = less than 0.01). Examination of IgG deposition using fluorescent anti-mouse IgG revealed a similar granular pattern and degree of staining in both immunized groups. Control animals that received concurrent T4 administration alone showed similar hTg-induced murine thyroiditis to non-T4-treated animals and could not explain the apparent immunosuppression observed. In conclusion, these data demonstrated that M reduced both the splenic immune response and the degree of thyroiditis after heterologous Tg immunization, while a quantitative difference in the circulating and intrathyroidally deposited Tg antibody was not detected.

Animals↗
PubMed1982

A specific plaque-forming cell assay for human thyroglobulin antibody-secreting immunocytes.

As the initial step in the investigation of thyroid autoantibody-secreting immunocytes, we have identified such cells in vitro by the use of plaque-forming cell assays dependent on the lysis of antigen-coated sheep red blood cells. Human thyroglobulin antibody-secreting peripheral mononuclear cells were detected in six of seven patients with autoimmune thyroiditis, but not in normal control subjects. Our data indicated that 0.06-1.7% of immunoglobulin-secreting cells have the potential for human thyroglobulin antibody secretion in such patients and validated the specific plaque-forming cell technique for the investigation of thyroid autoantibody production.

Autoantibodies↗
PubMed1982

Screening for specific learning disabilities among dental students.

At a time when recognition of the needs of handicapped students is of great concern, many handicapped persons have not yet been identified. Even with the advent of legislation mandating educational equity for all handicapped students, those with specific learning disabilities (SLD) still remain unidentified or unserved by institutions of higher education. In 1979, New York University College of Dentistry instituted a classwide screening and testing program for SLD students. The program sought to identify accepted students "at risk" for SLD through the administration of a two-hour battery of tests designed by learning disabilities specialists. Follow-up in-depth evaluations yielded a 90 percent accuracy rate on correct identification of SLD students based on the screening results. This article presents specific test results, analyses of data, and comparison of self-report measures and suggests educational implications, including suggestions for program accommodations.

Adult↗
PubMed1981

Inhibition of immunoglobulin-secreting cells by antithyroid drugs.

Previous studies have indicated that titers of thyroid-specific autoantibodies decrease in patients with autoimmune thyroid disease during antithyroid drug therapy. In keeping with these observations has been the accumulating evidence that such drugs may have an immunosuppressive action both in vivo and in vitro. To further analyze the mechanism of such activity, we have used an indirect hemolytic plaque assay based on protein A-coated sheep red blood cells and a specific plaque-forming cell (PFC) assay based on human thyroglobulin-linked sheep red blood cells. When freshly prepared peripheral mononuclear cells were exposed to increasing concentrations of methimazole or propylthiouracil (PTU), there was no significant effect on spontaneous plaque-forming cell responses (PFC). However, after incubation for more than 6 days with methimazole or PTU, there was a marked dose-related inhibition of pokeweed mitogen stimulated PFC, the degree of inhibition varying from one individual to another. Overall, there were 31.5 +/- 9.6% and 32.5 +/- 5.2% reductions in plaque formation with 10(-4) M methimazole or PTU, respectively, a level which probably approximates intrathyroidal thionamide concentrations in patients. A similar inhibitory response was seen in the human thyroglobulin-PFC assay using peripheral mononuclear cells from patients with autoimmune thyroiditis, confirming the potential inhibition of thyroid-specific autoantibody production by these compounds. Furthermore, at 10(-4) M there was no effect of PTU or methimazole on cell survival, as assessed by trypan blue exclusion. These data suggested that the thionamide drugs interfered with immunoglobulin production, rather than secretion, at concentrations which were likely to be present intrathyroidally in many treated patients.

Antithyroid Agents↗