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Biomedical subjects

P Lyons

Publications and source records attributed to P Lyons.

At least 37 records · Page 2Linked to original sources
PubMed1988

Production of hepatitis B virus-infected human B-cell hybridomas: transmission of the viral genome to normal lymphocytes in cocultures.

The presence of hepatitis B virus (HBV) genome and transcripts in mononuclear cells from a patient with acute type B hepatitis offered the possibility of developing a cell line which could serve as a model for HBV replication in lymphocytes. A human B-cell hybridoma, KDG92, was then produced which carries HBV DNA in an episomal state and expresses the major virus transcripts as well as its surface (HBsAg), core (HBcAG), and e (HBeAg) antigens. KDG92 releases in the supernatant surface antigen particles but not core or Dane particles. However, in cocultures this hybridoma is able to transmit episomal HBV DNA to normal lymphocytes, both T and B cells. This in vitro system can therefore provide important indications as to the virus life cycle in lymphocytes and the mechanisms of virus propagation from cell to cell.

B-Lymphocytes↗
PubMed1986

Adverse effect of splenectomy on the survival of patients with more than one kidney transplant.

Risk factors associated with death were identified in a cohort of patients who received 2 or more kidney transplants. Data on 19 variables were collected by chart review on 774 patients who received allografts between 1973 and 1980 at any one of 3 hospitals in Philadelphia. 124 of the patients received two or more transplants and were followed for a minimum of 1.5 years. Modified life table analyses of single variables indicated that 7 factors--splenectomy, donor source, age, transplant hospital, number of HLA mismatches, donor sex, and survival time of the prior graft--were significantly related to patient survival. Using all 19 variables, the proportional hazards model was fit to the data. The characteristics most related to survival were splenectomy (P less than .001), donor source (P = .0022), and age (P = .0015). The other 4 factors that were significant on univariate analysis were not significant in this multivariate analysis. The relative risk of death was 5.5 for patients who had had a splenectomy compared with those who had not had a splenectomy. Patients who had received more than one transplant were compared with patients who had received only one transplant, and a subset of recipients of primary transplants who returned to dialysis after primary graft failure. Survival of patients who had received one transplant was approximately the same as that of the retransplanted population. When the proportional hazards model was fit to the populations that received one transplant and compared with the model for the retransplanted group, only age and donor source were common to all three models. The effect of splenectomy on survival was significant for the total population of primary transplant recipients but had no effect on the survival of the subset of recipients whose kidney grafts had failed and were returned to hemodialysis. Infection accounted for 45% of the deaths among splenectomized, retransplanted patients. A higher percentage of septic deaths occurred in patients whose grafts were functioning at the time of death when compared with patients who had returned to dialysis after secondary graft failure. Although retransplantation alone is not associated with an increased mortality, retransplantation in splenectomized patients carries a high risk of death.

Adult↗
PubMed1986

Positive end-expiratory pressure increases plasma catecholamine levels in non-volume loaded dogs.

UNLABELLED: Positive end-expiratory pressure (PEEP) is commonly used in the treatment of critically ill patients whose sympathetic nervous system is stressed; however, PEEP's actions on sympathetic nervous system activity are unknown. We therefore measured the plasma noradrenaline response (an index of sympathetic nervous system activity) to graded doses of PEEP in nine mongrel dogs. After 30 minutes at each level of PEEP, plasma noradrenaline concentrations increased from baseline mean values of 300 (SD 108) pg/ml to 388 (SD 225) pg/ml (P less than 0.05) at 5 cm, 433 (SD 255) pg/ml (P less than 0.01) at 10 cm and 1194 (SD 882) pg/ml (P less than 0.01) at 20 cm water pressure of PEEP. The increases in plasma noradrenaline concentrations correlated inversely (r = -0.43, P less than 0.01) with PEEP-induced changes in cardiac output. Plasma adrenaline levels did not change significantly in response to 5 or 10 cm of PEEP; however, plasma adrenaline increased, while heart rate and mean arterial blood pressure fell, at 20 cm water pressure of PEEP (P less than 0.05). Within 15 minutes after discontinuation of PEEP, the plasma catecholamine concentrations returned to baseline levels. CONCLUSIONS: 1. PEEP significantly increases sympathetic nervous system activity in a rapid, dose-dependent, reversible manner; 2. the PEEP-induced increases in sympathetic activity may explain the reductions in organ blood flow which others have observed following the initiation of PEEP; 3. PEEP-related changes in sympathetic nervous system activity are a consequence of PEEP-induced reductions in cardiac output.

Animals↗
PubMed1984

Measurement of urinary leukocyte esterase activity: a screening test for urinary tract infections.

We evaluated the efficacy of testing for the presence of esterase (an enzyme released only from leukocytes) in the urine as an indicator of the presence of pyuria. We hypothesized that a "dipstick" test for urinary leukocyte esterase activity would be a rapid and simple screening technique for detecting urinary tract infections (UTI). To test our hypothesis we collected fresh urine specimens from 203 patients (148 outpatients, 55 inpatients) with a suspected UTI. Each specimen was divided into three aliquots; one was used for reagent strip testing (for leukocyte esterase, nitrite, and blood), one for microscopy, and one for culture. Of the 203 specimens, 49 showed significant bacteriuria (greater than or equal to 10(5) organisms/mL). The leukocyte esterase test was 100% sensitive (0% false negatives) with a 76% specificity (24% false positives) in predicting significant bacteriuria. Although a positive nitrite reaction was more specific (99% specificity, 0.6% false positives), it was insensitive (27% sensitivity, 73% false negatives). The high sensitivity of reagent strip leukocyte esterase testing for pyuria makes it a valuable screening test that should lead to the elimination of many needless urine cultures and microscopic examinations.

Adult↗
PubMed1984

Urine glucose testing in the critically ill: a comparison of two enzymatic test strips.

The urine glucose concentration is commonly used to monitor indirectly the degree of hyperglycemia in critically ill patients and to adjust insulin dosage. Most commercially available urine glucose reagent test strips measure the urine glucose concentration from 0% to 2%. When the urine glucose is at the 2% level, the blood glucose concentration may vary over a wide range. We compared a new urine glucose test strip which measures the urine glucose concentration from 0% to 5% versus a conventional strip (0% to 2%) in the analysis of double-voided urine specimens from 285 patients with diabetes mellitus. Both types of test strips were insensitive in detecting hyperglycemia and showed a wide range of blood glucose values for each estimated urine glucose concentration. However, the new test strips which gave measurements at the 3% and 5% urine glucose concentrations allowed for more specificity (99%) in detecting blood glucose levels above 250 mg/dl. We conclude that: (a) test strips measuring from 0% to 5% are superior to conventional 0% to 2% test strips because the 3% and 5% urine glucose readings allow for a high level of specificity in detecting severe hyperglycemia (greater than 250 mg/dl); (b) urine glucose testing is insensitive and nonspecific in detecting hyperglycemia when urine glucose values are 2% or less.

Blood Glucose↗
PubMed1982

Gastric and pancreatic function in patients with end-stage renal disease.

Gastroduodenal disease such as peptic ulcer and duodenitis is increased in patients with end-stage renal disease. Gastric hypersecretion of acid proposed as the underlying mechanism has been disputed because peptic ulcer has occurred even in those with normal or low gastric acid secretion. We studied the pancreatic exocrine secretion of bicarbonate (HCO3) and the concentration of plasma pepsinogens in addition to gastric acid secretion in 15 patients on chronic hemodialysis, 10 patients wih previous renal transplantation and compared them with 10 subjects without gastrointestinal or renal disease. We confirmed hypersecretion of gastric acid in renal disease. We confirmed hypersecretion of gastric acid in renal patients on chronic hemodialysis but not in transplant patients. In addition, we found basal but hyposecretion of HCO3 and hyperpepsinogenemia in both renal groups. These observations suggest that the high incidence of gastroduodenal disease in end-stage renal disease might, in part, be due to the simultaneous occurrence of gastric acid hypersecretion, basal hyposecretion of HCO3 by the pancreas, and hyperpepsinogenemia.

Adult↗
PubMed1980

Immune complex myositis associated with viral hepatitis.

Sarcolemmal osmiophilic deposits were demonstrated by electron microscopy in the striated muscle of a patient who developed viral hepatitis associated myositis. HBsAg, IgG, and C3 were found in the same location, suggesting that the deposits represent immune complexes and the primary cause of myositis.

Adult↗
PubMed1980

Haemodynamics of stable renal transplant recipients.

1. Haemodynamics, blood volume, plasma renin concentration and creatinine clearance were evaluated in 24 stable renal transplant recipients. 2. The mean cardiac index of the transplant recipients was not different from that of the normal subjects. 3. The transplant recipients comprised eight hypertensive and 16 normotensive patients. The mean cardiac index was the same in eight hypertensive and 16 normotensive patients. Thus the hypertension of stable renal transplant recipients is sustained by a high total peripheral resistance. 4. The mean blood volume, plasma renin concentration and creatinine clearance were similar in eight hypertensive and 16 normotensive patients. Therefore the hypertension of stable renal transplant recipients is not related to blood volume expansion, elevated peripheral renin or low creatinine clearance. The cause of the elevated total peripheral resistance in hypertension in stable renal transplant recipients remains to be elucidated.

Adolescent↗