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Biomedical subjects

L Fox

Publications and source records attributed to L Fox.

At least 19 recordsLinked to original sources
PubMed1992

Comparative effects of endothelin (ET-1) and U46619 on human saphenous vein and gastroepiploic artery, sources of human autologous grafts.

The effects of endothelin (ET-1) on smooth muscle contractile activity were investigated and compared in human saphenous vein and gastroepiploic artery, vessels frequently used in revascularization procedures. ET-1 contracted saphenous vein and gastroepiploic artery in a concentration-dependent manner. The peptide produced a greater maximal effect in the vein than in the artery and, in both preparations, ET-1 was less efficacious than U46619, an agent which mimics the actions of thromboxane A2 at the thromboxane A2/prostaglandin H2 receptor. The contractile response to ET-1 declined spontaneously at a more rapid rate in the artery than in the vein. The present data indicate that ET-1 has significant contractile activity in both vessels which are used for coronary arterial bypass surgery and suggest that although, a weaker vasoconstrictor than U46619, the peptide could induce vasospasm in both graft vessels.

Arteries↗
PubMed1992

Frequency of reisolation of Staphylococcus aureus from multiple sequential milk samples.

Bacterial cultures were performed on multiple sequential composite samples of milk from 1,172 cows in 9 dairy herds. If the initial diagnosis of Staphylococcus aureus infection was based on the first positive culture, an average of 37.8% of subsequent cultures on the same cows were negative for S aureus. However, if the initial diagnosis of S aureus infection was confirmed by 2 or 2 of 3 sequential positive cultures and any conversions from S aureus positive to negative were confirmed by 2 or 2 of 3 sequential negative cultures, then only 17.0% converted to a negative diagnosis. Conversion of cows from S aureus culture-positive to -negative varied between herds; 8.1 to 69% for single cultures and 0.0 to greater than 40% for confirmed cultures.

Animals↗
PubMed1992

Lupus nephritis in a pediatric renal transplant recipient.

A case of aggressive lupus nephritis in a pediatric renal transplant patient is described. She initially presented with end-stage glomerulonephritis for which an underlying etiology could not be determined. Ten months after cadaveric renal transplantation, systemic lupus erythematosus was diagnosed, when she developed diffuse proliferative glomerulonephritis in association with antinuclear antibody, anti-double-stranded DNA antibody and extrarenal manifestations of lupus. It is plausible that she developed recurrent rather than de novo lupus nephritis following transplantation. Reactivation of lupus nephritis in a renal transplant is unusual in adults, and is previously unreported in children.

Antibodies↗
PubMed1992

Metabolic differences between persistent and routine peritonitis in CAPD.

Changes in 10 metabolic parameters (body weight, blood hemoglobin, and serum albumin, urea, creatinine, cholesterol, triglycerides, potassium, calcium and phosphorus) were compared in 28 episodes of routine peritonitis and 27 episodes of persistent peritonitis. These infections occurred in 20 CAPD patients, all of whom acquired both types of peritonitis on separate occasions. Coagulase-negative staphylococci predominated in the routine infections, while Staphylococcus aureus and Gram-negative bacilli, especially Pseudomonas, were associated with persistent peritonitis. Decreases during infection were significantly larger in persistent as compared with routine peritonitis episodes for all 10 nutritional parameters. Time required for recovery of all nutritional variables except serum potassium and urea was significantly longer in the persistent episodes. Persistent peritonitis led to peritoneal catheter loss in 13 of the 27 episodes and was associated with 4 deaths, while routine peritonitis was associated with neither catheter loss nor death. In contrast to routine peritonitis, persistent CAPD peritonitis is associated with severe malnutrition, considerable morbidity, and mortality.

Blood Proteins↗
PubMed1990

Mechanism of aluminum-induced inhibition of hepatic glycolysis: inactivation of phosphofructokinase.

Aluminum, an abundant element in the earth's crust, has been implicated in various pathological disorders and low concentrations of this element have recently been shown to inhibit brain glycolysis. However, despite the fact that aluminum accumulates in high concentrations in the liver, potential effects of this metal on hepatic intermediary metabolism have not been explored. In perfused livers from untreated rats, maximal rates of production of lactate plus pyruvate (glycolysis) were 93 +/- 15 mumols/g/hr. Glycolysis was severely inhibited in livers from aluminum-treated rats (0.5 mg/kg, 6 hr before experiment) with maximal rates of only 23 +/- 4 mumols/g/hr. In contrast, glucose production (glycogenolysis) and hepatic oxygen uptake were not altered significantly by prior treatment with aluminum. In livers from fasted rats, pretreatment with aluminum did not influence gluconeogenesis or production of lactate and pyruvate from fructose (5 mM). This finding indicates that pyruvate kinase is not inhibited by aluminum and implicates phosphofructokinase, hexokinase and/or glucokinase as sites for the inhibitory effect of aluminum on glycolysis. In liver homogenates from untreated rats, increasing concentrations of aluminum did not show any appreciable effect on hexokinase or glucokinase activity but did cause progressive decreases in phosphofructokinase activity. Therefore, aluminum-induced inhibition of liver phosphofructokinase, an important control site in the glycolytic pathway, is most likely responsible for aluminum-induced inhibition of hepatic glycolysis.

Adenosine Triphosphate↗
PubMed1988

Ten-year experience with extracorporeal membrane oxygenation for severe respiratory failure.

In the last ten years, 17 patients with respiratory failure refractory to standard ventilator therapy have been treated with extracorporeal membrane oxygenation (ECMO) at the Toronto General Hospital. One patient was treated with ECMO twice. Four perfusions were veno-arterial, the remainder veno-venous. Perfusions ranged from 1 1/2 to 19 days, with a mean of six days. Ten patients died during treatment or soon after it was discontinued. Eight patients improved enough to allow resumption of standard ventilation, and four patients recovered sufficiently to have normal arterial blood gas levels on room air. Three are long-term survivors. Multiple surgical procedures have been performed successfully during use of ECMO including lung lavage, open lung biopsy and three lung transplants. Major complications include hemorrhagic diatheses and sepsis. The technique involves a substantial commitment of time and personnel but remains a tenable option for presumed reversible life-threatening respiratory failure.

Adolescent↗
PubMed1985

Prolonged cardiac arrest and resuscitation in dogs: brain mitochondrial function with different artificial perfusion methods.

Clinical techniques for artificial perfusion have not previously been examined directly for their effects on brain high-energy metabolism. Our study involved 24 large mongrel dogs that were anesthetized, instrumented for central venous intravenous access, and subjected to craniotomy to expose the dura and underlying parietal cortex. The animals were divided into the following six experimental groups of four animals each: nonischemic controls; 15-minute cardiac arrest without resuscitation; 45-minute cardiac arrest without resuscitation; 15-minute cardiac arrest plus 30 minutes resuscitation with conventional cardiopulmonary resuscitation (CPR); 15-minute cardiac arrest plus 30 minutes resuscitation with interposed abdominal compression (IAC) CPR; and 15-minute cardiac arrest plus 30 minutes resuscitation with internal cardiac massage. Cardiac arrest was induced by central venous injection of KCl 0.6 mEq/kg, and it was confirmed by continuous ECG monitoring. The three active resuscitation models included administration of NaHCO3 and epinephrine, but no attempt was made to restart the heart by defibrillation during resuscitation. At the indicated time in each group, a 4- to 5-g sample of brain was removed through the craniotomy, immediately cooled to 0 C and processed for isolation of mitochondria. The mitochondria were studied for their content of superoxide dismutase and for quantitative oxygen consumption with glutamate/malate substrate during resting and ADP-stimulated respiration. Our results show a significant drop in brain mitochondrial superoxide dismutase activity during the first 15 minutes of cardiac arrest. There is minimal injury to brain mitochondrial oxygen consumption during both 15 and 45 minutes of complete ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Pineal ultrastructure and indole profiles spanning the summer rise in arginine vasotocin immunoactivity.

A correlative radioimmunological-biochemical-ultrastructural study of the rat pineal gland was undertaken during the summer months when pineal arginine vasotocin (AVT) immunoactivity increases up to 200-fold. RIA confirmed a rapid rise in AVT activity during mid-August regardless of the time of day sampled. Pineal indoles were separated by HPLC and measured using electrochemical detection. Serotonin (5-HT) and 5-hydroxyindoleacetic acid levels were consistently elevated in daytime samples, and there was a significant trend for increased day and nighttime levels of 5-HT from July to September. Mid-dark levels of melatonin also exhibited a significant increase over the sample period. Nighttime levels of N-acetylserotonin mirrored fluctuations in 5-HT in the preceding photoperiod. Ultrastructural components implicated in peptide/protein and/or indole biosynthesis were quantified by stereological morphometry. The greatest amounts of rough endoplasmic reticulum stacks, lipid droplets, and annulate lamellae-like bodies coincided with peak AVT activity. Dense-cored vesicles and synaptic ribbons were consistently more frequent during the dark period. The number of dense-cored vesicles and nucleolar size tended to be greatest before and after the peak in AVT immunoactivity. These observations are consistent with the hypotheses that endoplasmic reticulum and lipid are functionally related to the synthesis and/or storage of peptide/protein factors and that numerical changes in synaptic ribbons and dense-cored vesicles are more closely related to day/night differences in indole metabolism.

5-Hydroxytryptophan↗
PubMed1979

Clinical efficacy and toxicity of netilmicin in the treatment of gram-negative infections.

Netilmicin, a new semisynthetic aminoglycoside antibiotic, was used to treat 41 infections in 38 patients. The outcome of four infections could not be evaluated: two patients received inadequate therapy and two did not have gram-negative infections. Clinical improvement occurred in 36 (97%) of the 37 gram-negative infections, and bacteriologic cure occurred in 30 (86%) of the 35 evaluable infections. Therapeutic serum concentrations of netilmicin were readily achieved by both intramuscular and intravenous routes. Reversible ototoxic effects occurred in 1 (3%) of 35 courses of therapy evaluated, reversible nephrotoxic effects occurred in 5 (14%) of 36 courses and mild reversible alterations in liver function occurred in 3 (19%) of 34 courses. Netilmicin appears to be effective and safe in the treatment of aerobic gram-negative infections.

Adolescent↗
PubMed1979

Biotyping of Escherichia coli by a simple multiple-inoculation agar plate technique.

A nine-test system using multiple-inoculation agar plates for biotyping of Escherichia coli is described. Testing of 959 strains resulted in 78 biotypes. On repeated testing, 96% of 182 strains had identical biotypes or differed by only one test. This system provides satisfactory differentiation among strains and is reproducible. Precise standardization of inoculum size is not required. Multiple inoculation allows time and cost-efficient testing of large numbers of strains.

Adult↗
PubMed1978

Neonatal osteomyelitis.

To evaluate current conservative therapy and document the existence of a recent shift in etiologic agents, we reviewed the records of 45 infants who developed osteomyelitis within the first ten weeks of life and who were admitted to Babies Hospital (New York) from 1951 through 1976. Emphasis was placed on characteristics and course of the disease, etiologic agents, therapy, and outcome. Illness was diagnosed within the first two weeks of life in 34 of the 45 infants (73%). Only six had been delivered normally after normal pregnancy and led a normal life before development of ostemyelitis. Infected sites were distinctive in frequency of involvement of multiple foci (21), of facial bones (10), and of joints contiguous to infected long bones (22 of 29). Conservative therapy (nonsurgical) seems reasonable for the majority of patients. Of particular interest is documentation of a shift from Staphylococcus aureus as predominant etiologic agent before 1965 to beta-hemolytic streptococci, commonly group B, from 1965 through 1976. Data collected from the literature of the 1930s indicate that such shifts have occurred before.

Delivery, Obstetric↗