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Biomedical subjects

A Robinson

Publications and source records attributed to A Robinson.

At least 379 records · Page 21Linked to original sources
PubMed1986

Selective osmoreceptor dysfunction presenting as intermittent hypernatremia following surgery for a pituitary chromophobe adenoma.

Intermittent hypernatremia following hypothalamic surgery or trauma is usually attributed to the triphasic dysfunction of vasopressin release (diabetes insipidus, inappropriate vasopressin release, and diabetes insipidus). A 39-year-old patient had hypodipsia and intermittent hypernatremia following hypothalamic surgery for a chromophobe adenoma. Mean arterial pressure fell by 25 percent during orthostasis testing and was associated with an increase in vasopressin levels from 1.3 microU/ml to 12 microU/ml. Plasma renin activity and aldosterone increased from 1.1 to 16 ng/ml per hour and from 6.7 to 39 ng/dl, respectively, and remained elevated for three and a half hours after tilt testing. Hypertonic saline infusion, on the other hand, increased serum osmolality from 290 to 304 mOsm/kg but did not result in a significant rise in vasopressin levels (all were less than 1 microU/ml). These results are consistent with a selective dysfunction of the osmoreceptor pathways of vasopressin release and intact volume receptor-mediated pathways. Patients with intermittent hypernatremia following hypothalamic surgery or trauma should be questioned specifically regarding thirst. If it is impaired or absent, these patients should be watched carefully, not only for the development of triphasic dysfunction of vasopressin release, but also for a selective osmoreceptor dysfunction associated with thirst deficits as found in patients with "essential hypernatremia."

Adult↗
PubMed1986

Susceptibility testing of methicillin-resistant Staphylococcus aureus with three commercial microdilution systems.

The antimicrobial susceptibilities of 100 methicillin-resistant Staphylococcus aureus isolates were determined concurrently by API Uniscept KB, Micro-Media, MicroScan, standardized disk diffusion, and reference broth microdilution to evaluate whether these commercial microdilution systems would reliably defect methicillin-resistant S. aureus. The methicillin minimal inhibitory concentration for all isolates was greater than or equal to 16 micrograms/ml as determined by the reference minimal inhibitory concentration panels containing 2% NaCl supplemented Mueller-Hinton broth. Using the breakpoints established by the National Committee for Clinical Laboratory Standards for reporting susceptible and resistant methicillin results, there was 100% agreement between the reference methods and API Uniscept KB at 24 hr. The Micro-Media and MicroScan systems had 47% and 8% very major discrepancies at 24 hr, respectively. At 48 hr, these two systems exhibited 15% and 0% very major discrepancies. Micro-Media and MicroScan were in agreement with the reference microdilution method (+/- 1 log2 dilution) for 62% and 68% of the strains at 24 hr, respectively and 88% and 85% of the isolates at 48 hr, respectively. The results of this study indicate that API Uniscept KB would provide a practical and reliable method for the detection of methicillin-resistant S. aureus.

Anti-Bacterial Agents↗
PubMed1986

Mycobacterium fortuitum peritonitis in a patient undergoing chronic peritoneal dialysis.

Peritonitis, due to Mycobacterium fortuitum, developed in a 15-yr-old young man undergoing chronic peritoneal dialysis. Although of low pathogenic potential, this rapidly growing non-tuberculous mycobacterium does cause human disease particularly in the compromised host and should be considered as a potential cause of peritonitis in the chronic peritoneal dialysis patient.

Adolescent↗
PubMed1986

Evaluation of a monoclonal antibody to ras peptide, RAP-5, claimed to bind preferentially to cells of infiltrating carcinomas.

RAP-5, a monoclonal antibody raised against a p21ras peptide, has been claimed to show immunohistochemical localisation of cells with infiltrative properties in human tumours. We confirmed that this antibody reveals pronounced cellular heterogeneity in human colonic neoplasms but could find no obvious relationship to infiltrative activity. RAP-5 bound to many different cell types, neoplastic and normal. In order to clarify the specificities of RAP-5 we applied it to two cell lines: nontumorigenic hamster fibroblasts in which ras expression is barely detectable, and a vigorously tumorigenic line derived from these fibroblasts by insertion of the human mutated Ha-ras oncogene in a high expression vector. Another antibody to p21ras, Y13-259, clearly distinguished between these cell lines both on immunoblots and immunocytochemically, but RAP-5 did not. Rather, it bound to proteins of a variety of molecular weights in both cell lines. The results show that RAP-5 is unlikely to be a useful reagent for detection of ras associated proteins in human tissues.

Adenocarcinoma↗
PubMed1986

Physiology and virulence determinants of Neisseria gonorrhoeae grown in glucose-, oxygen- or cystine-limited continuous culture.

Piliated Neisseria gonorrhoeae forming small, transparent colonies (P+O-) on clear typing agar have been grown in prolonged continuous culture to ascertain how different growth environments might affect gonococcal physiology and the expression of virulence determinants. Virulence of the penicillin-sensitive P9-2 and the penicillin-resistant KW1 strains was assessed by their ability to survive in polypropylene chambers implanted into the flanks of guinea pigs. Initial continuous culture experiments in the defined medium of Manchee et al. (FEMS Microbiology Letters 7, 115-118, 1980) indicated that growth was actually cystine-limited, rather than the anticipated glucose-limited. Surprisingly, cysteine was not completely metabolized and ammonium salts remained in excess. The molar growth yield on glucose (YGlc) was 65 g dry wt mol-1 and 45% of the glucose carbon metabolized was converted to biomass. Gonococci, whilst retaining the P+O- phenotype for over 100 generations of growth, did not survive in the subcutaneous chambers when inoculated at a variety of doses. When the cystine and glucose concentrations were increased and decreased respectively, growth became glucose-limited, the YGlc increased to 108 g mol-1 for strain KW1 and 75% of the metabolized glucose carbon was converted to biomass. After 17 generations of growth, however, only 2% of the gonococci retained the P+O- phenotype and P-O- bacteria predominated. Nevertheless, these bacteria were virulent in the chamber model, as was strain P9-2, which also retained only 2% of the P+O- phenotype during glucose-limited continuous culture. By contrast, the P+O- phenotype was retained during prolonged cystine- or oxygen-limited growth but only the latter was virulent. SDS-PAGE of membrane extracts confirmed that opaque colonies (O+) selected from the glucose-limited cultures contained a heat-modifiable protein (protein II) whereas transparent colony types lacked such proteins. The initial phenotype of virulent gonococci recovered from the subcutaneous chambers was P+O- but opaque variants dominated after several days. A 40 kDa outer-membrane protein was apparently induced during oxygen-limited continuous culture whereas a 44 kDa protein was absent during cystine-limited growth.

Animals↗
PubMed1986

Serum IgG, IgM, and C3 levels in Schistosoma japonicum infected rabbits.

New Zealand white rabbits were infected with 250 or 500 Schistosoma japonicum cercariae of Philippine-Leyte strain. Following the initial pre-infection bleed, blood was collected 2, 4, 6, 8, 11, 14, 17, 20, 23, 26, 29, and 32 weeks post-infection, and IgG, IgM, and C3 levels were assayed in the serum samples by single radial immunodiffusion. IgG and IgM achieved peak levels at 14 weeks post-infection and began to decrease in concentration by 26 weeks. At 32 weeks, some of the infected rabbits exhibited significantly reduced IgG and IgM levels which approached the concentrations assayed in the control animals. The infected animals demonstrated significantly elevated C3 levels (p less than or equal to 0.001) during the 6th to 26th weeks post-infection, with the exception of the 20th week.

Animals↗
PubMed1986

The psychomotor development of full term infants whose mothers were treated with glucocorticosteroids during pregnancy.

The Development Quotient (D.Q.) was tested in 48 full term infants at the ages of 12-24 months who had been treated antenatally with Betamethasone to hasten pulmonary maturity. The results were compared with a control group of 100 normal full term infants of the same age. Although the two groups differed with respect to gestational age, there were no differences in birth weight, Apgar score and method of delivery between them. The results of the D.Q. evaluation showed no significant difference between the two groups. The assumption is made, therefore, that antenatal treatment with Glucocorticosteroids in the second and third trimester does not adversely affect the infant's psychological and motor development.

Betamethasone↗
PubMed1985

Pertussis vaccine: present status and future prospects.

Use of killed whole-cell Bordetella pertussis vaccines has been a major factor in control of symptomatic whooping cough (pertussis). In the UK, diminished public confidence in the safety of this vaccine led to a reduction in vaccine acceptance which correlated with an increase in the incidence of pertussis. There is a need for acellular pertussis vaccines of low toxicity which, ideally, will prevent colonization and also protect against the disease symptoms. Vaccine design can rely increasingly on knowledge of the roles of individual bacterial components in the pathogenesis of pertussis. Serotype-specific agglutinogens 2 and 3 (fimbriae) and filamentous haemagglutinin are among surface components of B. pertussis which probably mediate adhesion to the respiratory mucosa. Systemic effects of pertussis can largely be attributed to the lymphocytosis promoting factor (pertussis toxin). Vaccines containing detoxified toxin plus one or more purified adhesins are envisaged at present.

Animals↗
PubMed1985

Peritonitis involving Capnocytophaga ochracea.

Spontaneous bacterial peritonitis, due to Capnocytophaga ochracea, developed in a 65-year-old alcoholic patient with extensive cirrhosis and ascites. Previously reported human infections with this organism have included peridontal diseases, septicemia, and arthritis. This is the first report of spontaneous bacterial peritonitis associated with Capnocytophaga species.

Aged↗
PubMed1985

Evaluation of the RIM system and Gono Gen test for identification of Neisseria gonorrhoeae from clinical specimens.

RIM-N (Austin Biological Laboratories) and Gono Gen (Micro Media Systems) were evaluated for accuracy and compared with conventional carbohydrate degradation tests for identification of Neisseria gonorrhoeae. A total of 127 fresh clinical isolates of N. gonorrhoeae were tested; 118 (93%) were identified by RIM-N, and 100 (79%) yielded positive reactions with Gono Gen. Seventy nongonococcal isolates including other Neisseria species, Branhamella catarrhalis, Kingella kingae, and Moraxella species were evaluated to determine the specificity of the test methods. Both rapid tests were 100% specific in the identification of N. gonorrhoeae isolates. RIM-N was the most sensitive test for the identification of N. gonorrhoeae and offers a useful, more rapid alternative to conventional carbohydrate degradation methods.

Agglutination Tests↗
PubMed1985

Antimicrobial synergy testing based on antibiotic levels, minimal bactericidal concentration, and serum bactericidal activity.

The ratio between the concentrations of different antimicrobial agents varies widely during therapy and often bears no resemblance to the ratios assessed by in vitro methods to evaluate the effectiveness of multiple antimicrobial therapy. The authors examined an alternative method using patient serum that reflects the actual antibiotic levels achieved in the patient. Previous investigators have shown that the ratio of the concentration of free drug (drug-f) to the minimal bactericidal concentration (MBC) in broth approximates the serum bactericidal titer (SBT) when pooled normal human serum is used as the diluent. Theoretically, when two antimicrobial agents are administered, the SBT should be equivalent to (drug-f A/MBC drug A) + (drug-f B/MBC drug B). SBT and drug level determinations were performed on peak and trough serum specimens from ten patients with endocarditis or osteomyelitis who were receiving multiple antimicrobial therapy. The serum dilution synergy method predicted additive interactions twice as often as the checkerboard and kill curve, and predicted synergy less frequently than the kill curve. The checkerboard predicted antagonism four times more often than the other methods and provided equivocal results in four of ten cases. The suggested method may offer an alternative procedure to assess antimicrobial interactions, which is based on antibiotic levels actually achieved in vivo instead of the arbitrary concentrations often used in in vitro tests.

Adult↗
PubMed1985

Prenatal diagnosis by amniocentesis.

One of the major applications of somatic cell genetics to clinical medicine is in the area of prenatal diagnosis by genetic amniocentesis, which permits the accurate prediction of fetal disease and allows pregnant women to selectively maintain unaffected fetuses. The more recent developments in recombinant DNA research promise to expand tremendously the potential of this technique.

Amniocentesis↗