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Biomedical subjects

G Peter

Publications and source records attributed to G Peter.

At least 91 records · Page 5Linked to original sources
PubMed1986

Tyrosine loading in patients with hepatic cirrhosis: lack of effect on plasma catecholamines.

Plasma norepinephrine concentrations are often elevated in patients with hepatic cirrhosis in relation to the stage of disease and possibly in response to a decrease in "effective" arterial blood volume. Since tyrosine, the precursor for catecholamines, is said to influence the rate of catecholamine biosynthesis within the central nervous system and peripheral sympathetic structures, we tested whether basal hypertyrosinemia and increased plasma tyrosine levels after oral loading with l-tyrosine are associated with elevated plasma catecholamine concentrations. Baseline norepinephrine (NE) and epinephrine (E) were significantly higher in 17 patients with decompensated cirrhosis, as compared with 11 healthy controls (NE: 809 +/- 108 pg/ml vs 295 +/- 16 pg/ml; E: 69 +/- 9 pg/ml vs 36 +/- 8 pg/ml). No significant correlation between the basal plasma tyrosine and norepinephrine level could be demonstrated in patients with cirrhosis (r = 0.04). Oral tyrosine loading (100 mg/kg b.w.) administered in six equal doses did not change the level of catecholamines, whereas plasma tyrosine increased two- to three-fold. Even a large single dose (14 g l-tyrosine) failed to alter plasma catecholamines in six cirrhotic patients with marked ascites. We therefore conclude that the enhanced availability of tyrosine in cirrhotics does not influence catecholamine biosynthesis in peripheral sympathetic neurons.

Blood Pressure↗
PubMed1986

Fenetylline: new results on pharmacology, metabolism and kinetics.

In the fenetylline molecule, theophylline is covalently linked with amphetamine via an alkyl chain. The inclusion of amphetamine and results from early metabolic studies have led to speculation that fenetylline may be merely a prodrug for amphetamine and/or theophylline. Although previous studies are not consistent with this hypothesis, additional studies were conducted to comparatively evaluate the profiles of activity exhibited by fenetylline and its two postulated primary metabolites, (+/-)-amphetamine and theophylline. Investigations were also initiated using newly developed high pressure liquid chromatography (HPLC) techniques to further characterize the metabolic pattern that fenetylline undergoes and to examine the relationship between plasma pharmacokinetics and the pharmacodynamic actions of the drug. Fenetylline inhibits activity associated with amphetamine in certain test systems, an effect similar to that previously observed with fenfluramine. Only small amounts of the amphetamine theoretically available in the fenetylline molecule are released. Pharmacodynamic activity associated with fenetylline administration is more closely tied to plasma levels of the parent compound than to any (+/-)-amphetamine produced.

Amphetamines↗
PubMed1985

Risk factors associated with nosocomial rotavirus infection.

A prospective study of hospital-acquired rotavirus infection was undertaken on an infant and young toddler floor to assess the incidence of infection and risk factors associated with nosocomial transmission. During the seven-month study period, gastroenteritis accounted for 60 of 663 admissions, 23 (38%) of which were due to rotavirus. In spite of enteric isolation of 21 (91%) of 23 patients with community-acquired cases, 36 infants developed nosocomial rotavirus infections. The attack rate of hospital-acquired infection was 12.8%, ranging each month from 2% to 21%. Approximately three fourths of both community-acquired cases (17/23) and nosocomial cases (27/36) occurred during the late winter and early spring. Prolonged stays in the hospital were associated with an increased attack rate of rotavirus infection. The risk of nosocomial rotavirus infection was not significantly enhanced by room contact with a rotavirus-infected patient or by the sharing of staff. However, only 47% (17/36) of patients with nosocomial infections were appropriately isolated, despite symptoms of gastroenteritis in all cases. These findings indicate that hospital acquisition of rotavirus is common, and indicate that failure to isolate patients with nosocomial rotavirus infections could be an important factor in hospital transmission.

Child, Preschool↗
PubMed1984

Response of infants to Haemophilus influenzae type b polysaccharide and diphtheria-tetanus-pertussis vaccines in combination.

In a multicenter study, responses to a combined vaccine containing standard diphtheria-tetanus-pertussis (DTP) and polyribosylribitol phosphate (PRP), the capsular polysaccharide of Haemophilus influenzae type b, were evaluated in 107 infants who received single doses at two, four, and six months of age and compared with those in 61 infants given single doses of DTP alone on the same schedule. Reaction rates were comparable in the two treatment groups. At seven months of age 61% of the subjects given the combined DTP-PRP vaccine and 8% and of those given DTP alone showed an antibody response to PRP, as defined as a twofold increase in titer over the lowest previous level. Among those given the DTP-PRP combined vaccine, 92% of the positive antibody responses occurred after the third dose. There was a variation in antibody response, possibly due to a difference in the vaccine lots administered.

Antibodies, Bacterial↗
PubMed1984

Comparison of tube dilution and microtitre methods for the detection of antibiotic tolerance in strains of Staphylococcus aureus.

Comparison of the MICs and MBCs of oxacillin for ten isolates of Staphylococcus aureus determined by tube dilution with those by microtitre dilution tests demonstrated that, whereas the MICs did not differ, the mean MBC by tube dilution was significantly higher (P less than 0.05) than that by microtitre after both 24 and 48 h of incubation. In addition, tolerance (MBC/MIC ratio greater than 32) was seen in four of ten strains with the tube dilution method but in only one strain with the microtitre technique after 24 h of incubation. These results and the poor correlation (r = 0.33) between MBCs by these methods indicate the importance of technical factors in the quantitation of MBCs and resulting identification of tolerance in Staph. aureus, and the need for a reference procedure in determination of MBCs.

Anti-Bacterial Agents↗
PubMed1984

Coagulase-negative staphylococcal bacteremia in newborns.

Coagulase-negative staphylococci (C-NS) recently have been identified as common causes of septicemia in high-risk newborns. In this review of the incidence and clinical significance of C-NS blood culture isolates from infants with suspected septicemia in a newborn intensive care unit (NICU), 2.2 percent of blood cultures in an 18-month period yielded C-NS. Based on the criterion of growth in multiple blood cultures as evidence of bacteremia, six of 30 infants (20%) were bacteremic, 17 (57%) represented probable contaminants (on the basis of growth in only one of two paired blood cultures with CN-S), and seven cases (23%) were indeterminant (only one culture was obtained). In those infants considered bacteremic, onset occurred between 12 and 51 days of age. In those with probable contaminants, all but three occurred in the first week of life. All infants had manifestations of suspected sepsis and survived the clinical episode. These findings indicate that C-NS growth can be due to nosocomial bacteremia but frequently represents blood culture contamination, especially in infants in the first week of life. At least two paired peripheral blood cultures should be obtained in infants with suspected septicemia to differentiate bacteremia from contamination.

Bacteriological Techniques↗
PubMed1983

Inability of counterimmunoelectrophoresis to detect echovirus in cerebrospinal fluid.

Methods for rapid detection of viral antigens in cerebrospinal fluid (CSF) are needed to aid in the differentiation of viral from bacterial meningitis. The formation of precipitin bands in patients with suspect viral meningitis utilizing viral antisera in a counterimmunoelectrophoresis (CIE) system has been described. To investigate further the possible value of CIE in the diagnosis of viral meningitis, the specificity of the CSF precipitin bands was studied. Precipitin bands were formed between commercially available type-specific antisera and cell culture supernatant fluids. Precipitin bands were also formed when control CSF was used as an antigen. Using type-specific antisera produced against purified virus, enteroviral antigens were not detected in CSF from patients from whom CSF viruses had been isolated. CIE lacks sufficient sensitivity for the detection of echovirus 11 antigens in CSF.

Antigens, Viral↗
PubMed1983

[Allergic contact eczema to pyridine and hydrazine derivatives].

The case of a chemistry student with a severe bullous, eczematous allergic contact dermatitis and with a diagnosed sensitization towards pyridine and hydrazine derivatives is reported. The results of the group allergy testing are compared with those in the literature and the widespread occurrence of pyridine and hydrazine compounds is summarized in tables.

Adult↗
PubMed1982

Limited protective effect of rough mutant antisera in murine Escherichia coli bacteremia.

Previous studies in mice have demonstrated differing immunoprophylactic activity of antisera against rough mutants of Enterobacteriaceae in the prevention of lethal gram-negative bacteremia. In this study, in which CF1 mice were made bacteremic with a serum-resistant Escherichia coli 06:K2:H1, the composite survival was significantly (p less than 0.001) enhanced by i. v. pre-treatment one to two hours before injection with either normal rabbit sera or antisera to the J5 mutant of E. coli 0111. The protective efficacy of these preimmune and hyperimmune sera did not differ significantly. Since considerable variability in the mortality of control mice occurred in the 25 separate experiments, the results of individual experiments were grouped retrospectively according to survival in the individual control groups and compared for evidence of possible differences in the efficacy of these two sera. With the exception of a statistically significant difference in the efficacy in one group receiving an LD75-95 inoculum, no such differences were noted. Thus, the variable effects of a rough mutant antiserum were not explained by differences in the relative virulence in the inoculum. This study confirms earlier observations by others that the protective efficacy of the anti-J5 antisera in infected mice does not differ appreciably from that of normal rabbit sera, provided the same donor rabbits are the source of both preimmune and hyperimmune sera.

Animals↗
PubMed1982

Opsonization of serum-sensitive and serum-resistant Escherichia coli by rough mutant (Re) antisera.

The antibody binding and susceptibility to opsonization of 11 SR and five SS Escherichia coli strains by pooled high-titered rabbit antisera against the core-defective Re chemotype mutant of Salmonella minnesota R595 were studied. Binding of antibody was assessed by an IFA method, and the phagocytic rate was quantitated by measurement of the oxygen consumption of PMNs during phagocytosis. A significant correlation was demonstrated between the property of serum sensitivity and both antibody binding (p less than 0.001) and enhanced susceptibility to phagocytosis (p less than 0.01) after opsonization of these E. coli with rough mutant antisera. Opsonic activity was heat-stable and was primarily in the serum igG fraction. Opsonic antibody was reduced markedly by absorption with the methanol-fixed Re mutant but was only partially reduced by absorption with solvent-extracted Re CGL. IgG antibodies capable of mediating phagocytosis and directed against both extractable and nonextractable antigens of the core-defective Re mutant of S. minnesota R595 reacted with strains of E. coli isolated from neutropenic patients.

Agranulocytosis↗