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Biomedical subjects

J Green

Publications and source records attributed to J Green.

At least 325 records · Page 18Linked to original sources
PubMed1995

Long-term results following digital flexor tenosynovectomy in rheumatoid arthritis.

A retrospective review of flexor tenosynovectomy for rheumatoid flexor tenosynovitis in the palm and digit was performed. Fifteen patients (61 fingers) were reviewed for at least 1 year (average, 4 years) after surgery. An average of 2.2 cm improvement in active flexion (pulp to distal palmar crease) was observed. A significant difference in preoperative and postoperative results was found. Sixty-seven percent of digits were classified as having excellent or good results, 21% fair results, and 12% poor results. The clinical recurrence rate was 31% and the reoperation rate was 15%. Only minimal complications from the extended surgical approach were observed. Debulking the fibro-osseous canal by excising a slip of flexor digitorum superficialis was associated with a reduction in the recurrence and reoperation rates.

Adult↗
PubMed1995

Adriamycin-related hypertension in pregnant rats: response to a thromboxane receptor antagonist.

1. In previous works we have described the development of hypertension and aggravation of proteinuria in rats who became pregnant after the administration of Adriamycin. This was associated with an increase in the glomerular thromboxane B2-prostaglandin E2 ratio. 2. To assess the pathogenetic role of thromboxane in this model, female Wistar rats were mated 2 weeks after receiving Adriamycin (3.5 mg/kg intravenously). Rats were then treated with the thromboxane-receptor antagonist daltroban, 60 mg day-1 kg-1 orally, beginning on day 11 of pregnancy. Systolic blood pressure, proteinuria and the urinary excretion of thromboxane B2, 6-keto-prostaglandin F1 alpha and prostaglandin E2 were measured serially before mating, and on days 14 and 21 of pregnancy. The results were compared with those in Adriamycin-(treated) pregnant rats not treated with daltroban, Adriamycin-treated virgin rats and normal virgin or pregnant rats either treated or untreated with daltroban. 3. In daltroban-treated pregnant and virgin rats treated with Adriamycin, systolic blood pressure remained normal, whereas it increased significantly (P < 0.05) in untreated animals. On day 14, blood pressure was higher in non-daltroban-treated Adriamycin-treated pregnant rats than in non-daltroban-treated Adriamycin-treated virgin rats. Treatment had no effect on blood pressure in normal virgin or pregnant rats. Proteinuria was higher in pregnant rats treated with Adriamycin than in Adriamycin-treated virgin rats, but it was not reduced by daltroban.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1995

Porcine pregnancy-associated glycoproteins: new members of the aspartic proteinase gene family expressed in trophectoderm.

Pregnancy-associated glycoproteins (PAG) are members of the aspartyl proteinase gene family that were initially identified in cattle (bPAG) and sheep (oPAG) as placenta-specific antigens in maternal blood. The objective of this study was to determine whether PAG are expressed in pig trophoblast. A porcine conceptus cDNA library was screened with 32P-labeled ovine and bovine PAG cDNA. Of the approximately 10(4) plaques that were initially screened, a very high number (approximately 5.3%) were positive. Two distinct types were identified, and full-length clones representing each type (1371 bp, pPAG1; 1378 bp, pPAG2) were fully sequenced in both directions. Their open reading frames coded polypeptides of 389 and 387 amino acids, respectively, including 15 amino acid signal peptides. Each had several potentials sites for N-glycosylation. Both were members of the aspartic proteinase gene family, with approximately 50% amino acid sequence identity to porcine pepsinogen and 64% to each other. They were only distantly related to PAG of ruminant species (53% and 49% identify in amino acid sequence to oPAG1 and bPAG1, respectively). Interestingly, pPAG1 had amino acid substitutions within its catalytic center (Gly-->Ala81, domain 1; Thr-->Ser263, Thr-->Ser265, Ser-->Ala266, domain 2) that together were likely to render it enzymatically inactive, whereas pPAG2 retained sequences identical to pepsin in these regions. Western blotting of secretory products of porcine trophoblast with anti-oPAG1 and anti-bPAG1 antisera indicated that pPAG, like PAG from ruminants, had an unexpectedly high M(r)(approximately 70,000).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Detection of small round structured viruses in shellfish by reverse transcription-PCR.

We describe the application of a previously developed sample extraction procedure to the detection of small round structured viruses (SRSVs) in shellfish. Initial seeding experiments showed that PCR inhibitor removal and virus recoveries were comparable to those in previous studies with poliovirus. Shellfish from a range of sewage-contaminated sites were then tested for the presence of SRSVs by using broadly reactive PCR primers followed by Southern blotting with internal probe sites. Positive results were obtained from 5 of 31 field samples tested. Four of these positive samples were from highly polluted sites. PCR product sequence analysis confirmed their identity as SRSV and showed sequence diversity compared with virus controls, suggesting that the results were not a consequence of PCR cross-contamination. Finally, shellfish associated with four separate outbreaks of viral gastroenteritis were tested by PCR and Southern blot for the presence of SRSVs. All outbreak samples tested gave positive results. As far as we are aware, this is the first demonstration of the detection in environmentally contaminated shellfish of the SRSVs responsible for human gastroenteritis. This development may help contribute to the further development of public health controls for molluscan shellfish.

Amino Acid Sequence↗
PubMed1995

Interaction of p72syk with the gamma and beta subunits of the high-affinity receptor for immunoglobulin E, Fc epsilon RI.

Activation of protein tyrosine kinases is one of the initial events following aggregation of the high-affinity receptor for immunoglobulin E (Fc epsilon RI) on RBL-2H3 cells, a model mast cell line. The protein tyrosine kinase p72syk (Syk), which contains two Src homology 2 (SH2) domains, is activated and associates with phosphorylated Fc epsilon RI subunits after receptor aggregation. In this report, we used Syk SH2 domains, expressed in tandem or individually, as fusion proteins to identify Syk-binding proteins in RBL-2H3 lysates. We show that the tandem Syk SH2 domains selectively associate with tyrosine-phosphorylated forms of the gamma and beta subunits of Fc epsilon RI. The isolated carboxy-proximal SH2 domain exhibited a significantly higher affinity for the Fc epsilon RI subunits than did the amino-proximal domain. When in tandem, the Syk SH2 domains showed enhanced binding to phosphorylated gamma and beta subunits. The conserved tyrosine-based activation motifs contained in the cytoplasmic domains of the gamma and beta subunits, characterized by two YXXL/I sequences in tandem, represent potential high-affinity binding sites for the dual SH2 domains of Syk. Peptide competition studies indicated that Syk exhibits a higher affinity for the phosphorylated tyrosine activation motif of the gamma subunit than for that of the beta subunit. In addition, we show that Syk is the major protein in RBL-2H3 cells that is affinity isolated with phosphorylated peptides corresponding to the phosphorylated gamma subunit motif. These data suggest that Syk associates with the gamma subunit of the high-affinity receptor for immunoglobulin E through an interaction between the tandem SH2 domains of SH2 domains of Syk and the phosphorylated tyrosine activation motif of the gamma subunit and that Syk may be the major signaling protein that binds to Fc epsilon RI tyrosine activation motif of the gamma subunit and that Syk may be the major signaling protein that binds to Dc epsilon tyrosine activation motifs in RBL-2H3 cells.

Amino Acid Sequence↗
PubMed1995

Cell-matrix interaction in bone: type I collagen modulates signal transduction in osteoblast-like cells.

Cell interaction with extracellular matrix (ECM) modulates cell growth and differentiation. By using in vitro culture systems, we tested the effect of type I collagen (Coll-I) on signal transduction mechanisms in the osteosarcoma cell line UMR-106 and in primary cultures from neonatal rat calvariae. Cells were cultured for 72 h on Coll-I gel matrix and compared with control cells plated on plastic surfaces. Agonist-dependent and voltage-dependent rises in cytosolic Ca2+ concentration ([Ca2+]i; measured by fura 2 fluorometry) were significantly blunted in cells cultured on Coll-I compared with cells grown on plastic. In UMR-106 cells, the collagen matrix effect was mimicked by 24-h incubation with soluble Coll-I or short peptides containing the arginine-glycine-aspartate motif. Accumulation of cellular adenosine 3',5'-cyclic monophosphate (cAMP) stimulated by parathyroid hormone, cholera toxin, and forskolin was augmented (50-150%) in cells plated on Coll-I vs. control. The collagen effect on both [Ca2+]i- and adenylate cyclase-signaling pathways in UMR-106 cells was abrogated in the presence of protein kinase C (PKC) depletion or inhibition. Also, Coll-I induced a twofold increase in membrane-bound PKC without changing cytosolic PKC activity. Thus, by altering PKC activity, Coll-I modulates the [Ca2+]i- and cAMP-signaling pathways in osteoblasts. This, in turn, may influence bone remodeling processes.

Amino Acid Sequence↗
PubMed1995

Validity of the Mattis Dementia Rating Scale for detection of cognitive impairment in the elderly.

The validity of the Mattis Dementia Rating Scale (DRS) for detecting neuropsychological impairment was evaluated in 22 elderly patients with mild cognitive impairment and 48 rigorously screened control subjects. A cutoff score was identified that correctly classified 95% of patients and 100% of control subjects. Results of this preliminary study suggest that the DRS may prove useful in screening for mild cognitive impairment in elderly populations. Further validation with a representative elderly sample is needed to establish screening value in primary care or community populations.

Aged↗
PubMed1995

Systemic hypotension and renal failure in obstructive jaundice-mechanistic and therapeutic aspects.

The association between obstructive jaundice and postoperative acute renal failure has been originally described more than eight decades ago and is now a well-established clinical phenomenon. Acute renal failure occurs in 8 to 10% of patients requiring surgery for relief of obstructive jaundice and contributes to eventual mortality in 70 to 80% of those who develop it. A major factor that may underlie the susceptibility to renal failure in patients with obstructive jaundice is cardiovascular instability manifested as systemic hypotension and defective vascular reactivity. This article outlines the scope of the clinical association between jaundice and renal failure and reviews the clinical and experimental studies that have contributed to our understanding of the underlying pathophysiologic mechanisms for this phenomenon. A growing body of evidence emanating from these studies indicates that bile constituents (e.g., bile acids, bilirubin, cholesterol) do not exert a direct nephrotoxic effect. Rather, the retention of bile during cholestatic jaundice has deleterious effects on cardiovascular function and on blood volume. This, in turn, sensitizes the kidney to prerenal failure and acute tubular necrosis in postsurgical patients with obstructive jaundice. The institution of prophylactic measures based on the appreciation of these underlying pathogenic mechanisms may result in an improvement in the overall prognosis of jaundiced patients undergoing surgery.

Acute Kidney Injury↗
PubMed1995

A physician's perspective on capitation.

Change is not on the horizon; it is already here. Capitation is only the latest form of competition with which we physicians have dealt through high school, college, medical school, postgraduate training, and even entry into practice. Capitation is a reality. It is here to stay. It will not disappear. It is a concept that must be understood, embraced, and managed to ensure financial survival. Physicians face issues of life and death on a daily basis. It is not too much for them to handle capitation.

Capitation Fee↗
PubMed1995

Effect of diltiazem and methyldopa on gestation-related renal complications in rats with adriamycin nephrosis. Relationship to glomerular prostanoid synthesis.

BACKGROUND: In the presence of pre-existing renal disease, occurrence of hypertension during pregnancy may compromise renal function and aggravate proteinuria. In pregnant rats with early adriamycin nephropathy, this is associated with an increase in the glomerular TxB2:PGE2 ratio. In the present study we evaluated the effect of blood-pressure control on renal function and its relationship with glomerular prostanoid synthesis. DESIGN OF THE STUDY: Pregnant Wistar rats with adriamycin nephropathy received diltiazem, 30 mg/kg/day or methyldopa, 400 mg/kg/day from mid-gestation. Mean arterial pressure (MAP), inulin clearance (CIN), urine protein excretion (UP) and glomerular prostanoid synthesis were measured. Results were compared with (i) untreated pregnant rats with adriamycin nephropathy, (ii) virgin rats with adriamycin nephropathy, and (iii) normal virgin or (iv) pregnant normal rats. RESULTS: MAP increased in untreated pregnant rats with adriamycin nephropathy (P < 0.01 versus virgin rats with adriamycin nephropathy), contrasting with the physiological decrease observed in normal pregnant rats. Diltiazem and methyldopa decreased MAP to normal values. In untreated pregnant rats with adriamycin nephropathy CIN decreased and proteinuria increased significantly at the end of gestation. Treatment with diltiazem and methyldopa augmented GFR, but only diltiazem decreased UP significantly. It was associated with an increased glomerular PGE2 synthesis. CONCLUSION: We conclude that in rats with adriamycin nephropathy, antihypertensive treatment improved GFR. Diltiazem also decreased urinary protein excretion, associated with a normalization of the glomerular TxB2:PGE2 ratio.

Animals↗
PubMed1995

Effect of recurrent pregnancies on the evolution of adriamycin nephropathy.

BACKGROUND: In rats with incipient adriamycin nephropathy, pregnancy increases urine protein excretion and mean arterial pressure, with no changes in the glomerular filtration rate. Renal histology is normal and the glomerular TxB2/PGE2 ratio is increased. METHODS: In the present study we evaluated the influence of repeated pregnancies on the evolution of adriamycin nephropathy. Two weeks after a first delivery, rats were mated again and were followed till 35 days after the second delivery. RESULTS: In pregnant rats with adriamycin nephropathy, urine protein excretion and mean arterial pressure returned to values identical to those found in age-sex-matched virgin rats with adriamycin nephropathy. At the end of the second pregnancy, mean arterial pressure and urine protein excretion were again elevated, compared with virgin rats with adriamycin nephropathy. Thirty-five days after the second delivery, urine protein excretion and mean arterial pressure remained elevated, 296 +/- 50 mg/day vs 115 +/- 26 and 121 +/- 4 vs 110 +/- 1 mmHg respectively, P < 0.05. Glomerular filtration rate remained unchanged 0.84 +/- 0.09 vs 0.79 +/- 0.09 ml/min in virgin rats with adriamycin nephropathy. The glomerular TxB2/PGE2 ratio was decreased, contrasting with the first pregnancy. At the end of the second pregnancy, histological examination of the kidneys in rats with adriamycin nephropathy revealed a significant increase in mesangial expansion. It was even more marked 35 days later, at the last follow-up, with a semiquantitative score of 162 +/- 29 vs 81 +/- 20 in virgin adriamycin nephropathy rats, P < 0.05. CONCLUSIONS: In rats with adriamycin nephropathy, repetitive pregnancies seem to aggravate the natural course of the disease in an irreversible fashion. The earlier changes in glomerular prostanoid synthesis, particularly on thromboxane, may play a pathogenic role by activating mesangial cell matrix synthesis.

Animals↗
PubMed1994

Further evidence for multiple pathways in soluble methane-monooxygenase-catalysed oxidations from the measurement of deuterium kinetic isotope effects.

The data from the deuterium isotope experiments in this study show that the primary kinetic isotope effect for methane oxidation catalysed by soluble methane monooxygenase from Methylococcus capsulatus (Bath) is very small, < 2. In contrast, the primary kinetic isotope effect for -CH3 group oxidation in toluene is large, > 7. A mechanistic pathway in which a substrate radical is formed from hydrogen atom abstraction by a ferryl species is believed to operate for CH4, the toluene -CH3 group and similar alkanes. Direct oxygen atom addition, rather than H atom abstraction, is indicated for aromatic ring oxidations in benzene and toluene and for styrene oxide formation from styrene. Thus, more than one mechanistic pathway appears to operate in soluble methane-monooxygenase-catalysed reactions and, in some cases, the pathway chosen may be dictated by the substrate. In the soluble methane-monooxygenase-catalysed oxidation of toluene the rates of: (a) substrate dissociation from the enzyme-substrate complex, (b) product formation and (c) product release (benzyl alcohol and p-cresol) from the enzyme-product complex are comparable in magnitude. Therefore all three of these steps are partially rate-determining in the soluble methane monooxygenase catalytic cycle for toluene oxidation.

Benzene↗