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Biomedical subjects

R Kumar

Publications and source records attributed to R Kumar.

At least 1,225 records · Page 68Linked to original sources
PubMed1986

Effect of 1,25-dihydroxyvitamin D3 on mouse mammary tumor (GR) cells: evidence for receptors, cellular uptake, inhibition of growth and alteration in morphology at physiologic concentrations of hormone.

Mammary glands are target tissues for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). We have examined a mouse mammary tumor cell line (GR) for receptors of 1,25(OH)2D3 and have examined alterations in the growth and morphology of these cells in response to 1,25(OH)2D3. GR cells contain a high affinity (Kd approximately 10(-11)), low-capacity receptor with a high specificity for 1,25(OH)2D3. The 1,25(OH)2D3 receptor in GR cells has a sedimentation coefficient of 3.5 and elutes from DEAE cellulose columns with approximately 0.15 M KCl. These properties of the receptor are similar to those reported for other 1,25(OH)2D3 receptors. 1,25(OH)2D3 is internalized by GR cells in situ and specifically bound 1,25(OH)2D3 is found predominantly, if not entirely, in the nucleus as determined by cell fractionation and autoradiographic techniques. The incubation of GR cells in culture for 7 days with 1,25(OH)2D3 markedly alters cell growth. Cell growth is retarded in a dose-dependent manner; physiologic concentrations (10(-10) M) of 1,25(OH)2D3 retard cell growth by approximately 50%. In addition, GR cells incubated with 10(-9) to 10(-8) M 1,25(OH)2D3 undergo marked morphological changes. The incubation of GR cells with other vitamin D metabolites such as 25-hydroxyvitamin D3 (25(OH)D3) at a concentration of 10(-9) M does not significantly alter cell growth or morphology. The presence of high affinity receptors for 1,25(OH)2D3, the specific internalization of 1,25(OH)2D3 predominantly into the nuclei, and the significant effects of physiological concentrations of 1,25(OH)2D3 on cell growth suggest a direct, specific, nuclear effect of 1,25(OH)2D3 on GR cells. The mouse mammary tumor model might be useful in examining the effect of 1,25(OH)2D3 on tumor formation.

Animals↗
PubMed1986

Ruptured uterus: sonographic diagnosis.

Sonography was able to suggest a diagnosis of uterine rupture by demonstrating intra- or extraperitoneal hematoma in the correct clinical setting. A pelvic abscess complicating a uterine rupture was seen in one case. Previous uterine scar, use of prostaglandins for induction of labor, trauma with a currette, and cornual pregnancy were the implicated etiologic factors. Although the rupture site was never directly visualized by sonography, the combination of sonographic and clinical findings was strongly suggestive of the correct diagnosis.

Abscess↗
PubMed1986

Benign cortical defect: site for an avulsion fracture.

A benign cortical defect in a bone may present itself as a weak site for muscle attachment resulting in an avulsion injury. Such a benign cortical defect may be mistaken for a malignant tumor when the avulsion injury excites irregular, laminated periosteal reaction. We report three patients in whom avulsion fractures occurred at the site of pre-existing benign cortical defects in the distal femur.

Adolescent↗
PubMed1986

Chlorisondamine blocks acquisition of the conditioned taste aversion produced by (-)-nicotine.

Intraventricular microinjection (5 micrograms) of the bisquaternary ganglion-blocking drug chlorisondamine prevented acquisition of nicotine-induced conditioned taste aversion (CTA) in rats. This appeared to be a specific effect because chlorisondamine did not attenuate the conditioned taste aversion caused by apomorphine. These results support findings from other behavioural procedures indicating that centrally administered chlorisondamine causes a long-term blockade of central nicotinic mechanisms.

Animals↗
PubMed1986

Effect of dietary cadmium intake on serum thyroxine and triiodothyronine concentrations in rhesus monkeys.

Circulating thyroxine (T4) and triiodothyronine (T3) concentrations in rhesus monkeys were determined after various periods of cadmium administration in diet. No significant change in serum T4 and T3 levels was observed after 2 months of cadmium treatment. However, cadmium treatment for 4 months and 6 months showed a significant decrease in serum T4 and T3 levels indicating the adverse effect of long-term cadmium intake which increased gradually with duration of treatment.

Animals↗
PubMed1986

The metabolism and mechanism of action of 1,25-dihydroxyvitamin D3.

Much has been learned about the formation of the active metabolite of vitamin D3, 1,25-dihydroxyvitamin D3. Information concerning its formation and catabolism has allowed a clear understanding of factors involved in the maintenance of plasma concentrations of the hormone. The effects of 1,25-dihydroxyvitamin D3 on calcium transporting cells in the intestine are marked and well defined. The tissue (intestinal tissue) is easily isolated and manipulated and hence, this is an ideal tissue in which to examine the mechanism of divalent cation transport. The mechanism by which 1,25-dihydroxyvitamin D3 brings about this effect should help in understanding sterol hormone action.

Calcifediol↗
PubMed1986

Activation of gene expression is adversely affected at high multiplicities of linked simian virus 40 enhancer.

We have cloned multiple copies of 72-base-pair (bp) repeat transcriptional enhancer element from simian virus 40 in plasmid vectors upstream from the bacterial chloramphenicol acetyltransferase gene under the control of the simian virus 40 early promoter. Two copies of the 72-bp repeat provided efficient activation of gene expression. Increasing the number of linked 72-bp units to four substantially improved the activation of gene expression, but further addition of enhancers diminished the activation of gene expression proportionally to the number of enhancers added. Enhancer regions containing 10 or more copies of the 72-bp sequence were very inefficient in gene activation. Plasmids containing such expanded enhancer regions also competed less efficiently in vivo for trans-acting enhancer-binding factors. These effects are specific for the enhancer element and are not produced by reiterations of the 21-bp promoter element. Multiple enhancer units placed upstream do not interfere with the accuracy of mRNA initiation directed by the simian virus 40 early promoter in these plasmid constructs but do severely inhibit the initiation of replication at the neighboring simian virus 40 origin of replication that overlaps the early promoter region. These results are consistent with the hypothesis that the structural alterations induced in the DNA by a large number of copies of the enhancer are not favorable for the activation of a linked gene or for the binding of factors believed to mediate the enhancement effect.

Acetyltransferases↗
PubMed1986

Indium-111 leukocyte scanning. False-negative study in a renal abscess.

A 33-year-old man had clinical features of a right renal abscess. Results of excretory urography and ultrasonography showed a focal complex mass lesion in the right kidney. An In-111 leukocyte scan failed to detect the right renal abscess, which later was aspirated under CT guidance and explored surgically. The role of In-111 leukocyte imaging in the detection of intra-abdominal abscesses, with limitations of the procedure, is discussed.

Abscess↗
PubMed1986

Role of indium-111 chloride imaging in osteoid osteoma.

Indium-111 chloride imaging plays an important role in differentiating intracortical osteoid osteoma from chronic cortical abscess. The study also may be useful in the detection of intramedullary osteoid osteoma. Four patients who greatly benefited from indium-111 chloride imaging are presented.

Adolescent↗
PubMed1986

First thoracic disc protrusion.

First thoracic disc protrusion is rare. Only 12 cases have been described. The rarity of the condition is probably due to relative immobility of the spine at this level. The disc protrusion is invariably lateral causing radiculopathy. Antecedent trauma is rare. Horner's syndrome may be an associated feature. Good results follow disc excision using a posterior approach.

Humans↗
PubMed1986

Retinoid effect on calcium, phospholipid-dependent protein kinase from mouse skin.

Calcium, phospholipid-dependent protein kinase (C-kinase) was partially purified from skin of hairless mice. This enzyme activity was stimulated 6- to 15-fold in the presence of calcium and either diolein (DO), phosphatidyl serine (PS), or a mixture of the two. Tumor promoter, phorbol 12-myristate 13-acetate (PMA), also activated the enzyme either in the presence or in the absence of PS. beta-Carotene, retinol, retinal, retinoic acid, etretinate (trimethyl methoxyphenyl analog of retinoic acid), and isotretinoin (13-cis-retinoic acid) were tested for their effects on enzyme activity. Retinoic acid, etretinate, and isotretinoin stimulated enzyme activity in the absence of PS-DO, but inhibited PS-DO stimulated activity. The remaining compounds had no significant effect of C-kinase. In the presence of PS alone, these 3 retinoids had no effect on enzyme activity whereas retinoic acid and isotretinoin exhibited a dual effect of C-kinase in the presence of DO alone. Although the active retinoids seem to compete for binding sites on the enzyme with DO, the overall interaction among retinoids, DO, PS, and PMA appears to be more complex.

Animals↗
PubMed1986

Seasonal changes in the pineal organ of control and gonadectomized fish (Mystus vittatus [Bloch]).

The surface area and luminal structures of the pineal sac were studied during the prespawning, spawning, and postspawning phases of control and gonadectomized fish, Mystus vittatus, throughout the year. From the later half of prespawning to the first half of postspawning phases the values for the surface area were lower in the gonadectomized group whereas from the later half of the postspawning to the first half of prespawning phases the values were higher than in the control group. The acidophilic cell bodies were visible in the first half of prespawning and at the end of spawning phases as well as during the postspawning phase. In the control group sulfated acid mucopolysaccharides and mucoid basophils with gamma substances were faintly stained during the early months of the reproductive cycle in contrast to the experimental group; but in the later months these substances were strongly stained in both groups except in the gonadectomized group at the end of postspawning phase. The pineal lumen was narrow during the pre- and postspawning phases and wider in the spawning phase of the gonadectomized group in comparison to control; this may be related to the flow of cerebrospinal fluid. Thus, the morphohistochemical changes in the pineal organ of fish were evident in both groups during the prespawning, spawning, and postspawning phases.

Animals↗
PubMed1986

Leucocyte migration inhibition in cow's milk protein intolerance.

The leucocyte migration inhibition (LMI) was determined in an assay after in vitro challenge with beta-lactoglobulin. The assay was considered positive when migration inhibition index was greater than 20% (mean +3 SD of healthy infants). Ninety-eight infants with protracted diarrhoea and failure to thrive, 16 healthy, 12 malnourished, and 16 infants suffering from acute gastroenteritis were studied. Of the 98 patients with protracted diarrhoea, 12 fulfilled Goldman's criteria for cow's milk protein intolerance, 63 had lactose malabsorption, and in 15 no associated causative factor was identified. The mean index of migration inhibition in the cow's milk allergic group (58.83 +/- 11.98) was higher than in healthy controls (8.25 +/- 3.91), the difference being statistically significant (p less than 0.05). The test was positive in all patients with cow's milk protein intolerance. The assay was also positive in four other patients suffering from protracted diarrhoea, two of whom had lactose malabsorption. All the infants with acute gastroenteritis and malnutrition had values within the normal range. The migration inhibition index in five patients with cow's milk intolerance had declined to 24.74 +/- 4.87 in assays performed 1-6 weeks after return of clinical tolerance to cow's milk (p less than 0.05) but the test was still within the positive range in three of the five infants. These results suggest that this cell mediated immune assay is a sensitive test for the diagnosis of cow's milk protein intolerance in infants. The specificity needs to be reassessed in the light of more objective criteria for the diagnosis of cow's milk protein intolerance.

Animals↗
PubMed1986

Ethological studies of depressed patients.

The use of ethological methods for characterising the non-verbal behaviour of depressed patients and quantifying change during treatment is described. Approximately 150 individual motor patterns--expressions, gestures and movements--have been defined and this element list provides the basis for encoding video-recordings of interactions. Data quality is controlled by inter- and intra-observer comparisons and by a split-screen technique which simultaneously displays a computer animation of a data file and the original video-recording. Two investigations of the characteristics of non-verbal behaviour in Depression are discussed. The first showed that the frequency and duration of many items of behaviour of depressed patients interviewed soon after admission to hospital differed significantly from matched controls. Recordings of an interview at an intermediate point in treatment showed a reduction in these differences and they had disappeared when examined shortly before discharge. The second study was of mothers suffering from Post Natal Depression who were interviewed once. This study provided evidence that quantification of non-verbal behaviour can distinguish between diagnostic subcategories and showed some of the fine detail of behaviour which can be revealed in this way.

Animals↗
PubMed1986

The physiology of the vitamin D endocrine system.

It is clear that the vitamin D endocrine system plays a central role in the maintenance of calcium and phosphate homeostasis. It may be involved in the cellular differentiation and growth of various cells. Investigation of these properties in the future is likely to yield interesting information concerning the biology of this sterol hormone.

Animals↗