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Biomedical subjects

A Kumar

Publications and source records attributed to A Kumar.

At least 1,531 records · Page 85Linked to original sources
PubMed1990

IgG subclasses and IgM in rats: immunoregulatory effects of cimetidine on serum levels.

Previous studies have demonstrated an immunomodulatory role for cimetidine on antibody production. In these experiments we measured IgG subclasses and IgM in rats and also examined the effects of cimetidine on serum levels. Four week-old Sprague-Dawley rats were given cimetidine in three different treatment regimens. IgG subclasses and IgM determinations were carried out by radial immunodiffusion method on sera when animals were 6 and 8 weeks old. IgG1 levels in 6 week-old animals who received intraperitoneal cimetidine on days 1, 2, 3, 4, 5, 6, 8, 9, 15 and 16 were significantly higher (305 +/- 12 mg/l vs 236 +/- 53 in control animals). By 8 weeks of age in control animals, IgG1 levels had fallen to 78 mg/l and were statistically lower than the levels in all cimetidine treatment groups. Eight week-old control animals also demonstrated a four-fold fall in IgG2b levels (613 +/- 310 mg/l) when compared to in 6 week-old control (2295 +/- 1057 mg/l) animals, or 8 week-old animals who had received cimetidine. Animals receiving intravenous cimetidine on days 4, 11 and 18 had significantly lower (133 +/- 3 mg/l) serum levels of IgG2c, at 6 weeks of age, as compared to control animals (177 +/- 16); however, no statistically significant differences in IgG2c levels were observed in 8 week-old animals. No statistically significant differences in the levels of IgG2a or IgM were observed in either 6 or 8 week-old control and experimental animals. It appears that cimetidine does influence certain IgG subclasses, however, route and timing of cimetidine administration are critical in modulating these effects.

Animals↗
PubMed1990

The association between aneurysm formation and systemic hypertension in Takayasu's arteritis.

We have studied the incidence and patterns of aneurysm formation in 88 consecutive patients with Takayasu's arteritis by utilizing digital subtraction pan-aortoarteriography by the intravenous and/or intra-arterial route. Seventy-two patients underwent initial intravenous angiography of which 64 (89%) were diagnostic. All the intra-arterial studies (n = 24) were diagnostically adequate. Arterial aneurysms were seen in eight patients (9.1%) and the saccular variety (75%) was the most common. Clinical and angiographic features of these eight patients were compared with those of the remaining patients. No major differences were observed except that longstanding uncontrolled hypertension was present in all patients with aneurysm formation. In comparison, hypertension was observed in 30 (49.2%) of the remaining 61 patients in whom clinical details were available. Angiographic localization of the aneurysm is important since there are no clinical features that distinguish these patients and rupture of a strategically located aneurysm can prove fatal. The association between hypertension and aneurysm formation suggests that hypertension in these patients should be aggressively managed at the onset of disease. In this regard percutaneous transluminal renal angioplasty may prove a possible management adjunct.

Adolescent↗
PubMed1990

Are factors that influence oocyte fertilization also predictive? An assessment of 148 cycles of in vitro fertilization without gonadotropin stimulation.

Fertilization characteristics of 152 consecutively obtained oocytes in an in vitro fertilization (IVF) program employing only natural and clomiphene citrate-induced cycles were retrospectively analyzed. Fertilization occurred significantly more often (1) in women with tubal infertility, (2) in spontaneous cycles, and (3) in cases of secondary infertility. Grade I sperm motility from the original semen sample and the duration of infertility were also significant influencing factors. A similar sperm correlate was not identified on samples after sperm migration. Preovulatory follicular fluid steroids, progesterone (P), estradiol (E2), E2:P ratio, and luteinizing hormone (LH), as well as baseline plasma LH and the magnitude of the LH surge did not correlate with fertilization. However, when the identified factors were used to predict fertilization (discriminant analysis), only 58.3% of oocytes were correctly classified. This data supports the concept of performing IVF as a test in its own right.

Adult↗
PubMed1990

Elongated styloid process: an overview.

Stylalgia is a condition that causes a dull, nagging pain in the oropharynx, often referred to the ear and the mastoid region. The clinical diagnosis is certain if the elongated styloid process is palpated through the tonsillar area. Radiological investigations, such as orthopantomograms, give information about the medial angulation. The treatment of choice is surgical shortening of the process. Trans-tonsillar fossa excision is a simple technique and does not involve greater morbidity than a routine tonsillectomy.

Adult↗
PubMed1990

Synthesis and biological properties of novel phosphotriesters: a new approach to the introduction of biologically active nucleotides into cells.

A series of aryl bis(3'-O-acetylthymidin-5'-yl) phosphate derivatives have been synthesized in order to find a suitable aryl derivative which would hydrolyze to the bis(nucleosid-5'-yl) phosphate under physiological conditions. The 4-(methylsulfonyl)phenyl derivative was selected and 4-(methylsulfonyl)phenyl bis[(E)-5-(2-bromovinyl)-2'-deoxyuridin-5'-yl] phosphate (6d) and bis[2-(guanin-9-ylmethoxy)ethoxy]-4-(methylsulfonyl)phenyl phosphate (7b) were prepared. The former compound (6d) was stable in human serum and only following hydrolysis to the 5'-5'-linked diester (half-life of 17 h at pH 7.7) was it enzymatically degraded very rapidly by phosphodiesterases. Compounds 6d and 7b were evaluated for antiherpesvirus effects, both in vitro and in vivo. Their antiviral spectrum and potency was remarkably similar to that of (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) and 9-[(2-hydroxyethoxy)-methyl]guanine (ACV), suggesting that they only act as prodrugs of BVDU and ACV, respectively. However, compound 6d did show unexpected toxicity, which could be explained by the liberation of BVDUMP following penetration of the triester into the cell.

Acyclovir↗
PubMed1990

Synthesis and biological evaluation of some cyclic phosphoramidate nucleoside derivatives.

(E)-5-(2-Bromovinyl)-2'-deoxy-5'-O-(3-methyl-2-oxo-5-formyl-1,3,2- oxazaphosphacyclopentan-2-yl)uridine has been synthesized and, under physiological conditions and without the necessity for enzyme activity, has been shown to yield the 5'-nucleotide in vitro. Unfortunately this compound is not sufficiently stable in solution for it to be tested in vivo. The biological properties of this and some related derivatives of (E)-5-(2-bromovinyl)-2'-deoxyuridine and acyclovir have been evaluated in in vitro and in vivo systems designed to show the effects of any intracellular liberation of the nucleotide. Although some of the derivatives are probably acting as prodrugs of the active nucleosides, there is no evidence for the liberation of meaningful concentrations of the 5'-nucleotide by any of the compounds.

Animals↗
PubMed1990

Regional cerebral glucose metabolism is normal in young adults with Down syndrome.

Regional CMRglc (rCMRglc) values were measured with [18F]2-fluoro-2-deoxy-D-glucose (18FDG) and positron emission tomography (PET), using a Scanditronix PC-1024-7B scanner, in 14 healthy, noninstitutionalized subjects with trisomy 21 (Down syndrome; DS) (mean age 30.0 years, range 25-38 years) and in 13 sex-matched, healthy volunteers (mean age 29.5 years, range 22-38 years). In the DS group, mean mental age on the Peabody Picture Vocabulary Test was 7.8 years and dementia was not present. Resting rCMRglc was determined with eyes covered and ears occluded in a quiet, darkened room. Global gray CMRglc equaled 8.76 +/- 0.76 mg/100 g/min (mean +/- SD) in the DS group as compared with 8.74 +/- 1.19 mg/100 g/min in the control group (p greater than 0.05). Gray matter regional measurements also did not differ between groups. The ratio of rCMRglc to global CMRglc, calculated to reduce the variance associated with absolute rCMRglc, and right/left ratios did not show any consistent differences. These results show that healthy young DS adults do not have alterations in regional or global brain glucose metabolism, as measured with 18FDG and PET, prior to an age at which the neuropathological changes in Alzheimer disease are reported to occur.

Adult↗
PubMed1990

Global and molecular hemostatic markers in acute myeloid leukemia.

Patients with acute myeloid leukemia have multiple hemostatic and thrombotic complications, which may or may not result from disseminated intravascular coagulation. Previous studies incorporating routine coagulation analyses failed to detect any clinically useful information in most of these patients. In this study, the first comprehensive evaluation of the various aspects of the hemostatic system in a population of patients with acute myeloid leukemia was performed. Eighteen patients (23-71 years of age) were studied at either diagnosis or relapse. Hemostatic studies were performed at onset and on days 3, 7, and 30 after initiation of therapy. The bone marrow blast counts ranged from 8% to 98%; prothrombin time and activated partial thromboplastin time showed only minor prolongations in a few of these patients. However, in all patients measurement of platelet-associated markers revealed elevated platelet factor 4 and thromboxane B2 and normal 6-keto-prostaglandin F1 alpha levels. Fibrinolytic markers showed an increase in D-dimer and tissue plasminogen activator and a decrease in alpha 2-antiplasmin levels. Plasminogen, plasminogen activator inhibitor, and fibrinogen levels were normal. Coagulation markers demonstrated a decrease in protein C and antithrombin III levels and an elevation of the thrombin-antithrombin complex. The pretreatment values for all hemostatic markers studied were similar to the values obtained on days 3, 7, and 30 during treatment. This investigation demonstrated a subclinical activation of the components of the hemostatic system possibly leading to a hypercoagulable state. Although only six patients (33%) experienced hemorrhagic complications, the risk of bleeding and/or thrombosis was strongly evident in all patients. The significance of finding abnormal levels of specific molecular markers of hemostasis will be established in the future application of such markers in clinical evaluations of leukemic patients known to be at risk for coagulation disorders.

Acute Disease↗
PubMed1990

Ultrastructure of the cortex in the human egg.

Two distinct types of cortical granules were discerned in the human oocyte. The first type, G1 granules, had a mean diameter of 350 nm, contained a uniformly compacted, electron-dense substance; these granules were probably synthesized even before the oocyte was aspirated from mature follicles and their contents were never found to be secreted in any of the preovulatory (immature), unfertilized and fertilized eggs examined. The G2 granules measured 450 nm (mean diameter), had a granular content and were found to be synthesized and secreted at all the stages of egg development studied. Endocytosis was also evident in the unfertilized and fertilized eggs. The secretion of the G1 cortical granules even before fertilization suggests that they may have an additional role, rather than merely contributing to the blockade of polyspermy.

Culture Techniques↗
PubMed1990

Ring or disc-like enhancing lesions in partial epilepsy in India.

One-hundred unselected children presenting with partial motor seizures were subjected to clinical work-up and cranial computed tomography (CT scan). Seventy-three children had an abnormal scan. On these, 56 patients had either a ring (35 patients) or a disc-like (21 patients) enhancing lesion which coincided with the probable site of origin of the seizures in all cases. The lesions were surrounded by perifocal oedema which was occasionally severe enough to produce a mass effect. The significance of these disc or ring lesions is discussed in the light of recent literature. All patients with such lesions were put on three-drug anti-tubercular therapy along with anticonvulsants. A repeat scan could be obtained in 20 patients, 10 weeks to 11/2 years after the initial scan. This showed a decrease in size or disappearance of the lesion in the majority (13 patients). Four patients showed a spot of calcification in the area of the original lesion and another two showed a typical 'target sign', i.e. calcification within a ring. It is concluded that these ring or disc lesions represent tuberculomas which are, thus, the commonest cause of partial motor seizures in children in this area.

Brain↗
PubMed1990

Neonatal duodenal perforation.

Duodenal perforation in neonates is uncommon, and has been described rarely in the third part of the duodenum. Gastrointestinal perforations without an obvious cause have been labeled as "spontaneous." We report a case of perforation in the third part of the duodenum in a premature infant for which there was no obvious cause. In such "spontaneous" perforations, multifactorial etiology is likely and possible factors are discussed. The high mortality rate in such patients can be improved by early diagnosis and prompt resuscitation followed by surgery. Peritoneocentesis plays an important diagnostic role. It is also therapeutic in relieving the respiratory distress caused by free intraperitoneal air. The majority of duodenal perforations are amenable to primary closure at surgery and this should be the treatment of choice.

Duodenal Ulcer↗
PubMed1990

Polyfungal systemic infections in pediatric oncology patients.

Three cases of two fungal agents causing simultaneous systemic infection in immunocompromised pediatric patients are presented and the literature is reviewed. All three patients had several underlying factors that predispose to systemic fungal infections. A species of candida was identified initially as an etiologic agent in all of the three patients causing subcutaneous abscesses, urinary tract infections, fungemia, catheter exit site infection, or pneumonia. However, a few days later blood cultures grew aspergillus species in two of the three patients; in the third patient aspergillus was identified on microscopic examination of the spleen. All three patients had an associated bacteremia with either Staphylococcus aureus or S. epidermidis requiring vancomycin therapy. Presence of aspergillus infection required treatment with amphotericin. Difficulties in making a definitive diagnosis of systemic fungal disease may explain paucity of reports in the literature with simultaneous polyfungal systemic infection.

Adolescent↗
PubMed1990

Nitrobenzene poisoning and spurious pulse oximetry.

The successful management of nitrobenzene poisoning in a 21-year-old patient is presented. We report our experience of ventilatory care with additional intravenous methylene blue and ascorbic acid therapy. Pulse oximeters available at present are not useful in patients treated with methylene blue and should be used cautiously in the presence of cyanosis of unknown aetiology.

Adult↗