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Biomedical subjects

B Kaplan

Publications and source records attributed to B Kaplan.

At least 397 records · Page 22Linked to original sources
PubMed1987

An abasic site in DNA. Solution conformation determined by proton NMR and molecular mechanics calculations.

We have determined the three-dimensional structure of a non-selfcomplementary nonanucleotide duplex which contains an abasic (apyrimidinic) site in the centre, i.e. a deoxyribose residue opposite an adenosine. The majority of the base and sugar proton resonances were assigned by NOESY, COSY and 2DQF spectra in D2O and H2O. We have measured the initial slope of buildup of NOEs in NOESY spectra at very short mixing times (25 to 50 ms), and from these were able to establish interproton distances for the central part of the duplex. We propose a different strategy for proton-proton distance determinations which takes into account the observed variations in correlation times for particular proton-proton vectors. A set of 31 measured interproton distances was incorporated into the refinement of the oligonucleotide structure by molecular mechanics calculations. Two structures were obtained which retain all aspects of a classical B DNA in which the unpaired adenine and the abasic deoxyribose lie inside the helix. We observe that the non-hydrogen bonded adenine is held well in the helix, the Tm of this base being the same as that of the A.T base pairs in the same duplex.

Algorithms↗
PubMed1987

Preparative fractionation of amyloid proteins on a microgram scale by high-performance liquid chromatography and polyacrylamide gel electrophoresis.

Preparative separation of amyloid proteins on a microgram scale is presented. Amyloid fibrils solubilized in aqueous 50% acetonitrile containing 0.1% trifluoroacetic acid, are fractionated by reverse-phase high-performance liquid chromatography. Fractionation of amyloids obtained from patients with familial Mediterranean fever allowed isolation of a protein identical with a conventionally isolated AA-protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis is used for preparative separation of AL-proteins. Two protein extraction procedures from Coomassie Blue stained gels are applied using elution in 0.1% sodium dodecyl sulfate containing buffer and 6 mol/l guanidine-HCl solution. The eluted proteins are concentrated and sodium dodecyl sulfate and dye are removed by acetonitrile precipitation of sample.

Amyloid↗
PubMed1987

Initial impact of a clinical laboratory computer system. Themes common to expectations and actualities.

A longitudinal study is being conducted of a clinical laboratory computer information system's impact. This paper reports on effects that laboratory directors anticipated prior to installation, and effects reported by laboratory technologists 7 months postimplementation. Primary changes caused by the computer system were increases in the amount of paper work performed by technologists, and improvements in laboratory results reporting. The system generally was well accepted, but laboratory technologists differed in their responses to it. Technologists in some laboratories focused on work increases, whereas in other laboratories they emphasized improved information flow. The paper considers how changes in processes and outcomes of work might affect responses to a computer system. It also considers the implementation process, and suggests some areas where management could benefit from an improved understanding of responses to a computer information system.

Attitude of Health Personnel↗
PubMed1987

Effects of the components of breast milk on mucosal enzyme activity of the newborn small intestine.

The effects of the aqueous phase of human breast milk on the disaccharidase activity of newborn rabbit small intestinal mucosal explants were studied in vitro culture. These explants continuously synthesized protein and normal morphology was maintained for the duration of the cultures. Addition of the aqueous phase resulted in significant increase of lactase (p less than 0.001) and maltase (p less than 0.01) concentrations in these organ cultures. This effect was dose dependent and was observed whether the organ biopsies were derived from fed or starved newborn rabbits. Further purification of the aqueous phase showed that the active ingredient exerting these effects was lactose. These studies suggest that lactose may have an important function in stabilization of newborn intestinal disaccharidase enzymes.

Animals↗
PubMed1986

Acute leukemias with both myeloid and lymphoid surface markers. Cytoplasmic alpha-1-anti-chymotrypsin and alpha-1-anti-trypsin as possible indicators of early granulocytic differentiation.

Blast cells from ten patients (seven adults, three children) with acute lymphoblastic leukemias (ALL) contained immunoreactive cytoplasmic alpha-1-anti-trypsin (alpha-1-AT) and alpha-1-antichymotrypsin (alpha-1-ACT). Cytochemically positive reactions for block-like periodic acid-Schiff and a localized acid phosphatase suggested that the cells were of lymphoid origin rather than myeloid origin: negative for sudan black-B, nonspecific esterase, chloroacetate esterase, and myeloperoxidase. By surface phenotype, the leukemia showed positive reactions for both lymphoid (common acute lymphoblastic leukemia antigen, Ia, OKT-10) and myeloid (OKM-1, Leu M-1) antigens. Three of three patients tested portrayed the Philadelphia chromosome. Nine patients were Mexican-American and one was Japanese: all were of Asian ethnic derivation. Both myeloid and lymphoid treatment regimens were employed, with survival less than expected. Early granulocytic differentiation detectable by cytoplasmic alpha-1-AT and alpha-1-ACT in lymphoid blasts is discussed.

Adult↗
PubMed1986

Morphometric analysis of dysplasia in cervical cone biopsy specimens in cases with false-negative cytology.

Conization specimens with a histologic diagnosis of cervical intraepithelial neoplasia III were reviewed with respect to cytology findings in the three months preceding conization. In 29% of the cases, one or more false-negative cytology reports preceded conization. No dysplastic cells were found on review of the false-negative cytology slides from these cases. Morphometric analysis of surface dysplasia in the conization specimens was performed to explain these findings. A statistically significantly greater surface area of dysplasia and greater spread of dysplastic cells in the endocervical canal was found in the positive cytology when compared to the false-negative cytology cases. No difference in vaginal spread of dysplasia existed between the two groups. The endocervical canal was sampled with a moist cotton swab in all of the cases. The results suggest that small numbers of dysplastic cells high in the endocervical canal may not be effectively sampled by cotton swabs in cases of false-negative cervical cytology, lowering screening sensitivity.

Adult↗
PubMed1985

Oral lichen planus and squamous carcinoma. Case report and update of the literature.

A case of squamous cell carcinoma of the tongue arose in the plaque form of oral lichen planus. The literature on lichen planus is reviewed with emphasis on the issue of malignant transformation. Squamous carcinoma develops in 0.3% to 3% of patients with oral lichen planus (range, 0% to 10%). The average age of individuals with this complication is 50 to 55 years; 50% to 60% are men. Forty-four percent to 60% of patients have the erosive form of the disease, 28% to 34% plaque type, and 16% to 28% reticular. The mean interval from onset of the oral lesions to the development of cancer is nine to 12 years (range, three months to 40 years). Forty-six percent to 54% of the cancers occur on the buccal mucosa, 30% on the tongue, 16% on the lower lip, and 8% in miscellaneous sites. Twenty-four percent to 50% of the individuals also have cutaneous lichen planus.

Carcinoma, Squamous Cell↗
PubMed1985

Recurrent ovarian carcinoma: retreatment utilizing combination chemotherapy including cis-diamminedichloroplatinum in patients previously responding to this agent.

Eleven women with advanced ovarian cancer treated postoperatively with combination chemotherapy (cytoxan, hexamethylmelamine, Adriamycin, and cis-platinum) had disease-free intervals of 5 to 46 months (mean: 22 months) and subsequently developed recurrent carcinoma. Each patient was then retreated with combination chemotherapy which included cis-platinum. There was a 72% response rate to retreatment (36% complete, 36% partial). These overall and complete remission rates are comparable to those of platinum-based combination chemotherapy in patients without prior treatment. Those patients who responded to retreatment had a significantly longer mean survival rate than those who did not.

Adult↗
PubMed1985

Escherichia coli adherence to the intestine of mice.

Bacterial attachment to the intestine is the first step in the initiation of many intestinal infections. The effect of mucin and its major constituents on the adherence of a mannose-positive Escherichia coli strain to various intestinal segments of mouse intestine was examined. Removal of intestinal mucus led to increased adherence of E. coli to the ileal and colonic mucosal layers. Ileal mucin significantly decreased E. coli attachment to the ileum. Galactose and galactosamine were the major constituents of ileal mucin that reduced E. coli adherence to the ileum. We conclude that ileal mucin protects the epithelial cell from adherence by this mannose-positive E. coli strain. This protection is dependent on the presence of other sugar moieties that may be of importance in the adherence process.

Animals↗
PubMed1984

Lymphonodular hyperplasia of the colon as a pathologic finding in children with lower gastrointestinal bleeding.

The serious implication of gastrointestinal blood loss in children is well recognized; however, the significance of lymphonodular hyperplasia of the colon (LNHC) as a pathologic finding in this group of children is unclear. We reviewed the records of 95 children, ages 2-48 months, who were referred to our clinic with a history of hematochezia. Proctosigmoidoscopy was performed on 65 of them. Twenty children (31%) examined proctosigmoidoscopically were found to have LNHC, with no other identified source of bleeding. Clinical histories, endoscopic findings, and colonic biopsy specimens from the LNHC group were examined. Clinical presentation of patients in this group was not distinctive. LNHC was most prominent in the distal colon and rectum and was endoscopically characterized by friability (13/20) and ulceration (3/20). Characteristics of biopsy specimens from children with LNHC were than compared with tissue obtained from an age-matched control population and children with colitis. Biopsy specimens from children with LNHC contained increased numbers of lymphoid follicles and larger follicles than those from the control group. Specimens also contained mucosal inflammation and epithelial thinning and ulceration overlying enlarged follicles. We conclude that LNHC is a frequent proctosigmoidoscopic finding in children evaluated for lower gastrointestinal bleeding. The endoscopic and histologic appearance of these lesions would suggest that LNHC is not a normal finding and represents a potential source of rectal bleeding in children.

Acute Disease↗
PubMed1983

Is there cumulative or delayed toxicity from cis-platinum?

Evidence of increasing risk of nephrotoxicity was sought in the records of 95 patients who had received 300-826 mg/m2 cumulative doses of cis-platinum in single doses of 50-75 mg/m2 every 3-4 weeks, with hydration and diuresis using mannitol and furosemide. The incidence of serum creatinine elevation to greater than 1.5 mg/dl was 4.2% per patient and 0.75% per dose, no higher than the incidence observed at lower cumulative doses. Among 54 of these patients observed for at least 3 months after cessation of cis-platinum chemotherapy, only one had later deterioration of renal function to a serum creatinine of 1.9; both kidneys had been irradiated to 1900 rad in this patient. It was concluded that cumulative, delayed or severe nephrotoxicity are not significant problems related to prolonged cis-platinum administration at moderate doses when hydration and diuretics are routinely used.

Adult↗
PubMed1983

Hemorrhage into pituitary adenomas.

The clinical and pathologic features of pituitary apoplexy were evaluated within the last 100 consecutive pituitary tumors surgically treated at this institution. From this group, ten tumor specimens exhibited pathologically verifiable hemorrhagic necrosis, including six with classic apoplectic onset; the hemorrhage in four patients was asymmetric. The tumors of symptomatic patients were large, with suprasellar and parasellar extension readily identifiable by neuroradiologic examination. All tumors within this group were chromophobic adenomas by light microscopy, and each of these tumors microscopically exhibited a sinusoidal arrangement with very prominent vascularity. Comparatively, those tumors with asymptomatic hemorrhage were all intrasellar and were encountered in younger patients who had exhibited prior endocrine disturbances. By light microscopy, two of these asymptomatic lesions were chromophobic and two were acidophilic adenomas. In contrast with larger tumors, however, increased vascularity or sinusoidal patterns were not a prominent feature within this group. Our experience suggests hemorrhage within pituitary tumors is a common event, but symptomatic bleeding generally occurs in older patients whose larger tumors contain a pathologic vascular predisposition. Urgent surgical decompression (usually transsphenoidal) in symptomatic patients produced great neurologic improvement in each case.

Adenoma↗