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Biomedical subjects

R Jain

Publications and source records attributed to R Jain.

At least 145 records · Page 8Linked to original sources
PubMed1995

A density-sensing factor regulates signal transduction in Dictyostelium.

Dictyostelium discoideum initiates development when cells overgrow their bacterial food source and starve. To coordinate development, the cells monitor the extracellular level of a protein, conditioned medium factor (CMF), secreted by starved cells. When a majority of the cells in a given area have starved, as signaled by CMF secretion, the extracellular level of CMF rises above a threshold value and permits aggregation of the starved cells. The cells aggregate using relayed pulses of cAMP as the chemoattractant. Cells in which CMF accumulation has been blocked by antisense do not aggregate except in the presence of exogenous CMF. We find that these cells are viable but do not chemotax towards cAMP. Videomicroscopy indicates that the inability of CMF antisense cells to chemotax is not due to a gross defect in motility, although both video and scanning electron microscopy indicate that CMF increases the frequency of pseudopod formation. The activations of Ca2+ influx, adenylyl cyclase, and guanylyl cyclase in response to a pulse of cAMP are strongly inhibited in cells lacking CMF, but are rescued by as little as 10 s exposure of cells to CMF. The activation of phospholipase C by cAMP is not affected by CMF. Northern blots indicate normal levels of the cAMP receptor mRNA in CMF antisense cells during development, while cAMP binding assays and Scatchard plots indicate that CMF antisense cells contain normal levels of the cAMP receptor. In Dictyostelium, both adenylyl and guanylyl cyclases are activated via G proteins. We find that the interaction of the cAMP receptor with G proteins in vitro is not measurably affected by CMF, whereas the activation of adenylyl cyclase by G proteins requires cells to have been exposed to CMF. CMF thus appears to regulate aggregation by regulating an early step of cAMP signal transduction.

Animals↗
PubMed1995

Use of the CS-3000 Plus to prepare apheresed blood cells for immunomagnetic positive cell selection.

The Baxter CS-3000 Plus Blood Cell Separator was used to prepare progenitor cell components in a three-step process. The process was designed to remove platelets and plasma from a leukapheresis cell product before incubation with anti-CD34 monoclonal antibody (9C5) and to remove unbound monoclonal antibody after incubation. Fluorochrome-labeled cultured KG1a (CD34+) cells were added to the leukapheresis cell product (at 2% of total WBC) before CS-3000 processing to evaluate the CS-3000 process for preparing cells for immunomagnetic selection using the Isolex 300 (SA) Magnetic Separation system. Data were obtained using five leukapheresis products. Two percent of the nucleated cells were lost during the platelet reduction wash, and 67% of the platelets were removed. The amount of antibody initially added to the cells for incubation ranged from 3.9 to 7 mg (0.5 microgram/10(6) nucleated cells). The residual antibody in the cells after the antibody wash ranged from 11 to 40 micrograms. The antibody wash resulted in a 3% loss of nucleated cells and an additional 66% removal of platelets. The antibody-sensitized cells were then processed on the Isolex 300 (SA) system. The purity and yield of the Isolex KG1a cell product were 94% and 82%, respectively.

Antibodies, Monoclonal↗
PubMed1995

Diagnosis of abdominal tuberculosis: sonographic findings in patients with early disease.

OBJECTIVE: The diagnosis of abdominal tuberculosis is often difficult, because clinical manifestations and results of laboratory studies are nonspecific. If sonographic findings are sufficiently characteristic for diagnosis, sonography would be useful, especially in India, where abdominal tuberculosis is common and more expensive imaging techniques are not easily available. Accordingly, we performed sonography to establish the sonographic findings in cases of early tuberculosis in 56 patients with abdominal tuberculosis who had normal barium studies of the small bowel. SUBJECTS AND METHODS: Fifty-six patients with clinical features suggestive of abdominal tuberculosis (history of fever, abdominal pain, and weight loss) with no history of intestinal obstruction and normal barium studies of the small bowel had abdominal sonography. All sonograms were independently assessed by three radiologists, and the findings were tabulated by consensus. Diagnosis of tuberculosis was confirmed by sonographically guided biopsy of mesenteric lymph nodes in 19 patients, analysis of aspirated ascitic fluid in 12, and response to antituberculous chemotherapy in 25. Sonography was repeated 1, 3, 6, and 12 months after antituberculous chemotherapy was begun. Abdominal sonograms were also performed in 30 healthy volunteers, and measurements of mesenteric thickness were recorded. The mesenteric thickness was statistically compared in two groups of patients: patients at presentation with patients at the end of antituberculous chemotherapy and patients at presentation with healthy individuals. RESULTS: The mesenteric thickness in healthy individuals ranged from 5 to 14 mm. Sonographic findings in all patients with abdominal tuberculosis included an echogenic thickened mesentery (> or = 15 mm) with mesenteric lymphadenopathy. Other findings were dilated small bowel loops in 38 patients, minimal ascites in 17, matted small bowel loops in five, and omental thickening with altered echogenicity in three. Regression of these changes was noted on follow-up of all patients undergoing treatment. CONCLUSION: The characteristic sonographic features of early abdominal tuberculosis are mesenteric thickness of 15 mm or more and an increase in the mesenteric echogenicity (due to fat deposition), combined with mesenteric lymphadenopathy. Presence of dilated small bowel loops and ascites further substantiate the diagnosis.

Abdomen↗
PubMed1994

A potential role for antigen selection in the clonal evolution of Burkitt's lymphoma.

Burkitt's lymphoma (BL) is a monoclonal lymphoproliferative disorder characterized by the presence of specific chromosomal translocations that involve the c-myc proto-oncogene. Two subtypes of BL exist (endemic and sporadic) that differ in the prevalence of EBV genome expression. Although EBV infection may promote cellular proliferation in endemic BL, little is known about the forces that drive clonal expansion and evolution in the majority of EBV-negative sporadic BL. This study on an EBV-negative sporadic BL cell line derived from an AIDS patient provides evidence that antigenic stimulation may play a role in the development and/or expansion of such tumors. This cell line (BRG-P) contained a series of cellular clones that elaborated both IgM and IgA. Southern blot analyses of the line and its sublines indicated that both the IgM+ and IgA+ cells had identical c-myc and Ig JH gene rearrangements, indicating that they were derived from a common precursor, some of which eventually underwent an isotype switch. Ig VH gene sequence analyses of 21 molecular clones derived from the parental BRG BL line and two of its sublines demonstrated that all the clones used the same VH3 gene. Five unique intraclonal variants were identified at four distinct nucleotide positions (125, 161, 355, 375), which undoubtedly represented somatic mutations. Four of these five mutations occurred within complementary determining regions; all resulted in amino acid replacements. Moreover, an identical G to A nucleotide substitution that resulted in an identical amino acid change occurred at two distinct points in clonal evolution that were separated by the isotype class switch. Thus, the locations and types of the VH gene mutations, together with the occurrence of an isotype switch, are highly suggestive of an ongoing role for Ag stimulation and selection in the evolution of the malignant clone.

Adult↗
PubMed1994

Fluorescence postlabeling assay of RNA modification.

A new approach has been developed to assay RNA modification by combining enzymatic digestion of RNA to nucleoside monophosphate and fluorescence postlabeling. Nuclease P1 digestion of modified RNA affords both normal and modified nucleotides. The nucleotides are labeled in-situ with dansyl chloride via phosphoramidate derivatives with ethylenediamine following a procedure initially designed to synthesize fluorescence labeled deoxynucleotides. The postlabeled nucleotides are analyzed by HPLC using a fluorescence detector. Fluorescence postlabeling assay of 7-methylGmp in RNA exposed to dimethyl sulfate has validated the technique. In the presence of excess normal nucleotides, the limit of detection (LOD) lies between normal to modified nucleotide ratio of 10(3) to 10(4). HPLC enrichment of the modified nucleotide from the normal nucleotides prior to labeling enhances the LOD by two orders of magnitude.

Chromatography, High Pressure Liquid↗
PubMed1994

A developmentally regulated cell surface receptor for a density-sensing factor in Dictyostelium.

Conditioned medium factor (CMF) is an 80-kDa glycoprotein which is the signal in a cell density-sensing system used by developing Dictyostelium cells. CMF is slowly secreted by cells when they starve, and the extracellular level of CMF then becomes an indicator of the density of starving cells. To examine how CMF is sensed, we have made bacterially synthesized recombinant CMF and found that it has as much activity as native CMF, indicating that glycosylation is not part of the active site of CMF. Expression of recombinant fragments of CMF indicates that the active site lies within an 88-amino acid region near the N terminus. To determine whether CMF is sensed by cell surface receptors, we examined binding of iodinated recombinant CMF to live cells. We found saturable binding to 6-h starved cells at 3.9 x 10(4) molecules/cell with a KD of 2.1 nM. The binding saturates in 30 min, and a Scatchard plot indicates that there is only one class of receptor. The binding is competed off by the addition of either the native or recombinant CMF, or the 88-amino acid active fragment region; no binding competition is seen from the nonactive regions or other proteins. Very little binding to vegetative cells is seen, with maximal binding seen in cells starved for 6-8 h. The amount of cell surface CMF binding then decreases during later development. Normal levels of CMF binding are seen to CMF- cells, indicating that CMF is not required for the accumulation of its own receptor.

Animals↗
PubMed1994

Anti-invasive activity of 3,7-dimethoxyflavone in vitro.

Invasion of MCF-7/6 human mammary carcinoma cells into embryonic chick heart fragments was studied in organ culture during 8 days. The effect of 31 polyphenolic compounds, belonging to the flavonoids, chalcones, or coumarins, was tested in this assay for invasion. The anti-invasive activity of 3,7-dimethoxyflavone was found at concentrations ranging from 1 to 100 microM. At these anti-invasive concentrations, no cytotoxic effects could be detected: the anti-invasive effect was reversible upon omission of the molecule from the medium, and treatment of MCF-7/6 cells or heart fragments did not affect subsequent outgrowth from explants on tissue culture plastic. The molecule did not inhibit growth of MCF-7/6 cell aggregates nor of heart fragments kept in suspension culture. The action mechanism of 3,7-dimethoxyflavone is the subject of our ongoing research.

Animals↗
PubMed1994

Orbital-tuberculosis.

Three cases of orbital tuberculosis are presented, two as cold abscess in the orbit and one as a chronic indolent sinus. A simple clinical test like Fine Needle Aspiration Cytology (FNAC) can demonstrate some or all of the characteristic pathological features like caseating necrosis, epitheloid cells and Langhan's giant cells. Important corroborative evidence can be obtained from the Tuberculin test and a positive therapeutic trial. While there are many other causes or orbital swelling and abscess, tuberculosis should be considered an important differential diagnosis in endemic areas. Simple tests like the tuberculin reaction and Fine Needle Aspiration Cytology should be considered among the routine diagnostic investigations for orbital swellings.

Abscess↗
PubMed1994

Transient central hypothyroidism as a cause of failure to thrive in newborns and infants.

The course of two neonates and one 4-month-old infant with laboratory and clinical evidence of central hypothyroidism is described. All three presented with failure to thrive and improved after L-T4 therapy. Early recognition and treatment of newborns and infants with central hypothyroidism is important to maximize the potential for growth and development. Two of the three infants have been documented to have transient central hypothyroidism of hypothalamic origin, not previously reported.

Failure to Thrive↗
PubMed1994

Systemic lupus erythematosus complicated by thrombotic microangiopathy.

Seven patients with systemic lupus erythematosus (SLE) or SLE-like disease developed thrombotic microangiopathy. Prominent features of their acute illnesses were microangiopathic hemolytic anemia (7), thrombocytopenia (7), fever (1), nervous system disease (4), and renal dysfunction (5). Laboratory data were significant for antinuclear antibody (ANA) (7), DNA (5), low C3 level (3), low C4 level (2), antiphospholipid antibody (6), schistocytes (7), and lactate dehydrogenase > 500 (7). All seven patients received treatment that initially included steroids but later included cyclophosphamide (4), plasma infusion (1), plasmapheresis (5), intravenous gamma-globulin (2), anti-platelet agents (2), or vincristine (3). Six patients improved, and one patient expired during treatment. Of the six patients who survived this complication, three expired within the year following their acute illnesses. Histology, available in two cases, showed vascular changes consistent with a microangiopathic process. We conclude that the spectrum of vascular diseases in SLE extends beyond vasculitis to include noninflammatory vascular processes that can cause equally devastating complications.

Adult↗
PubMed1994

Modulatory effects of testosterone on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity.

In this experiment, we examined the modulatory effects of testosterone on the parkinsonism-inducing drug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in two strains of mice. Orchidectomized male CD-1 and C57/B1 mice were implanted with either empty Silastic capsules or capsules containing testosterone and subsequently treated with MPTP. A small area of the corpus striatum was removed for determination of dopamine (DA) content, whereas the remainder was superfused and used to measure L-DOPA (5 microM)-evoked DA release. In animals treated with MPTP, L-DOPA-evoked DA release was reduced significantly in CD-1 mice, but not in C57/B1 mice, treated with testosterone. No differences in L-DOPA-stimulated DA release between MPTP-versus vehicle-treated mice was observed in either the CD-1 or C57/B1 mice receiving empty Silastic capsules. Corpus striatum DA contents were more severely depleted in the MPTP-sensitive C57/B1 versus the CD-1 mouse strain irrespective of hormone treatment. These results confirm previous results demonstrating differences in these two mouse strains in response to the neurotoxic effects of MPTP upon corpus striatum DA content. More interestingly, they show an important differential modulatory effect of testosterone upon L-DOPA-evoked DA release as a function of MPTP treatment and indicate that testosterone significantly alters the neurotoxic effects of MPTP in the CD-1 mouse.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1994

Primary pelvic hydatid cyst presenting with obstructive uropathy and renal failure.

Primary pelvic hydatid cyst is a rare entity. Pelvic hydatid cysts usually present with pressure symptoms involving adjacent organs (bladder and rectum usually). A case of primary pelvic hydatid cyst presenting with obstructive uropathy leading to chronic renal failure is presented. A combination of preoperative albendazole therapy of 1.2 g/day for 8-12 weeks and surgical excision were effective in alleviating the symptoms and improving the renal function.

Adult↗
PubMed1994

Hemodialysis removal of norfloxacin.

The effect of hemodialysis on norfloxacin removal was evaluated in 7 patients. Single 800-mg doses of the drug were given to the subjects prior to dialysis using cuprophan hollow fiber dialyzers. Arterial and venous sample pairs were obtained at hourly intervals during treatment. Norfloxacin plasma concentrations were determined by HPLC. The mean hemodialysis clearance and extraction ratio were 38.84 +/- 10.92 ml/min and 0.19 +/- 0.06, respectively. Small differences in these parameters were observed between dialyzers with different surface areas (p > 0.05) and also between treatments using different blood flow rates (p > 0.05). Since a relatively small amount of norfloxacin is removed by hemodialysis, dosage adjustment is not necessary to compensate for the extracorporeal removal.

Adult↗