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Biomedical subjects

A Robinson

Publications and source records attributed to A Robinson.

At least 325 records · Page 18Linked to original sources
PubMed1990

The parental origin of the extra X chromosome in 47,XXX females.

We used X-linked DNA polymorphisms to study the parental origin of X chromosome nondisjunction in 28 47,XXX live-born females. Errors in oogenesis accounted for 26 of the cases, with the majority of these being attributable to an error at meiosis I. We observed an association between advanced parental age and meiosis I nondisjunction--but not meiosis II nondisjunction--in the maternally derived cases. In studies of recombination we found little evidence for an association between pairing failure and X chromosome nondisjunction, but our results suggest that increased recombination near the centromere may play a role in the etiology of the 47,XXX condition.

Adolescent↗
PubMed1989

Incidence of cerebral infarction after radiotherapy for pituitary adenoma.

The incidence of cerebral infarction was studied in 156 patients irradiated for treatment of pituitary adenomas. Seven patients experienced strokes at intervals of 3.2 to 14.6 years after irradiation. The observed incidence was not significantly greater than the expected value of 3.5 strokes (P = 0.078). Six strokes occurred in patients receiving equivalent doses (ED) of 1070 ret or more (observed to expected ratio 3.87, significantly elevated; P less than 0.001). Univariate log-rank analysis showed that the risk of stroke was significantly higher (P = 0.010) in patients receiving an ED of 1070 ret or more (4180 cGy/22 fractions) than those receiving lower doses. Multivariate analysis, however, demonstrated that the increased risk of stroke was associated only with increasing age (P less than 0.0001), not ED (P = 0.148). Due to these inconsistent statistical results, no definitive conclusions could be reached about the relationship between radiation dose to the pituitary and subsequent cerebral infarction.

Adenoma↗
PubMed1989

Case-control study of colorectal cancer and fecal mutagenicity.

Fecal mutagenicity was measured in 68 patients with colorectal cancer and in 114 controls, using Salmonella tester strains TA98 and TA100 with and without S9 activation. Samples were also tested for fecapentaenes by high-performance liquid chromatography, to permit the separation of fecapentaene and non-fecapentaene mutagenicity. Overall, no significant case-control differences in fecal mutagenicity were observed. However, when samples containing high concentrations of fecapentaenes were excluded, non-fecapentaene TA98 mutagenicity was observed in eight cases (12%) and only four controls (4%), resulting in an estimated relative risk of 4.4 (95% confidence interval = 1.0-21.1). The association of colorectal cancer risk with non-fecapentaene TA98 mutagenicity could not be explained as an artifact of diagnostic workup or gastrointestinal bleeding among the cases. Smoking could also be excluded as a source of the TA98 mutagenicity seen, but possible dietary origins are still being explored.

Adenocarcinoma↗
PubMed1989

Case-control study of colorectal cancer and fecapentaene excretion.

The fecapentaenes are potent mutagens found in high concentrations in the stools of some individuals. These compounds are produced in vivo by common species of the colonic microflora, from precursors of unknown origin. The fecapentaenes have been postulated to increase the risk of colorectal cancer. To test this hypothesis, we measured fecapentaene excretion in 69 patients with adenocarcinoma of the colon or rectum, newly diagnosed at three Washington, DC area hospitals. The cases were compared with 114 surgical controls, frequency matched to the cases on age, sex, and hospital. We attempted to measure fecapentaene excretion 4 times for each subject: before surgery; and at 1 mo; 3 mo; and 6 mo following surgery. Contrary to our study hypothesis, we found fecapentaene excretion during the four study periods to be similar or even lower in cases compared to controls. An indirect measurement of fecapentaene precursors also tended to be lower in cases. The case-control differences could not be explained as effects of bleeding or of the colorectal diagnostic workup, which was assessed in a separate group of 86 patients. We conclude from these data that the excretion of fecapentaenes does not increase the risk of colorectal cancer, at least when measured near the time of diagnosis.

Aged↗
PubMed1989

Decisions following the intrauterine diagnosis of sex chromosome aneuploidy.

This is a report of 327 phone calls to our center concerning the intrauterine diagnosis of sex chromosome abnormalities (SCA). The first author (A.R.) responded to each by counseling either the parents or the referring professional. Sixty-two percent continued the pregnancy. When the parents were counseled directly, the percentage continuing the pregnancy was significantly higher than when the information was transmitted through the professionals. Our results are different from most reports in these situations, and suggest that well-informed couples, counseled by geneticists, are more likely to continue these pregnancies. The possible occurrence of SCA should be considered in preamniocentesis counseling.

Aneuploidy↗
PubMed1989

Relationship between the M42 antigen of mouse sperm and the acrosome reaction induced by ZP3.

A murine monoclonal antibody, M42 mAb, directed against 200/220 Kd protein of mouse sperm, has been employed to study the molecular events of gamete interaction. We have reported previously that M42 mAb blocks mouse fertilization in a zona-dependent manner; the reagent specifically inhibits physiologically induced (zonae), but not pharmacologically induced (A23187), acrosome reactions in mouse sperm. Using solubilized mouse zonae pellucidae and purified ZP3, we demonstrate that M42 mAb inhibits acrosome reactions (ARs) induced by ZP3 to the same extent as those induced by total zonae. We have also studied AR inhibition using the fluorescent antibiotic chlortetracycline (CTC), which permits visualization of three different acrosomal patterns during the AR. In the presence of M42 IgG, greater than 70% of capacitated sperm treated with zonae are arrested in the acrosome-intact state (B-pattern), in contrast to the majority of sperm (60-70%) in the absence of M42 IgG, which progress through the intermediate phase (S-pattern) to the fully acrosome-reacted (AR-pattern) state. Incubation of sperm with zona proteins modified by incubating eggs with phorbol esters arrests sperm in the S-pattern (Y. Endo, R.M. Schultz, and G.S. Kopf, 1987, Dev. Biol. 119, 199-209). We show that once sperm have reached such a state, M42 mAb no longer exerts an inhibitory effect. The addition of unmodified ZP to S-pattern sperm permits the completion of the acrosome reaction. These results indicate that M42 mAb blocks an early step in the AR cascade and that M42 mAb is unable to prevent subsequent events of this cascade once it has been initiated.

Acrosome↗
PubMed1989

Fecapentaene concentration and mutagenicity in 718 North American stool samples.

The fecapentaenes (FP) are the predominant fecal mutagens identified to date, but they have not been shown to be carcinogenic. Epidemiologists looking for other fecal mutagens that may be related to colorectal cancer must disentangle from their investigations the pervasive mutagenic effect of the fecapentaenes. As a first step to studying the epidemiology of fecal mutagenicity independent of fecapentaenes, we compared FP measurements and Salmonella mutagenicity assay results for 718 acetone-extracted stool samples collected from a variety of subjects in the Washington DC metropolitan areas. In this large group, 50% of mutagenic samples contained elevated fecapentaenes. Specifically, three-quarters of the samples mutagenic in TA100 contained high FP levels. In contrast, mutagenicity in TA98 was not generally explainable by fecapentaenes, suggesting that non-fecapentaene TA98 mutagenicity should be one focus of future efforts to uncover colorectal carcinogens of etiologic importance.

Feces↗
PubMed1989

Serospecific protection of mice against intranasal infection with Bordetella pertussis.

The ability of purified serospecific agglutinogens from Bordetella pertussis to protect mice against intranasal infection has been examined. Immunization with agglutinogen 2 protected mice against infection with 1.2.0 or 1.2.3 serotypes of B. pertussis, whereas immunization with agglutinogen 3 protected mice against infection with all serotypes. More importantly immunization with serospecific agglutinogen resulted in immune selection so that organisms recovered following infection did not express the immunizing antigen. The results are consistent with the suggestions that protection of children with whole cell pertussis vaccine is to some extent serospecific and that agglutinogens should be considered as constituents of acellular pertussis vaccines.

Administration, Intranasal↗
PubMed1989

Serotyping Bordetella pertussis strains.

The serotyping scheme for Bordetella pertussis, developed in the 1950s, depends on the presence or absence of various strains of three major agglutinogens, two of which have been shown to be fimbrial proteins, and several minor agglutinogens, the biochemical nature of which is unknown. This article reviews the reasons for the confusion which has recently arisen over the nomenclature of the serotype antigens and proposes a simplified serotyping scheme based on the fimbrial components.

Agglutination↗
PubMed1989

Phase II study of low dose aminoglutethimide 250 mg/day plus hydrocortisone in advanced postmenopausal breast cancer.

Low dose aminoglutethimide 125 mg twice daily plus hydrocortisone 20 mg twice daily was shown to produce oestrogen and androgen suppression in postmenopausal women. A phase II study was carried out in 101 patients with advanced postmenopausal breast cancer. Objective response rates were 4% CR and 21% PR. Fourteen per cent had disease stabilization for more than 6 months (SD). Soft tissue sites showed the best response. Responses occurred in previous tamoxifen failures (28%) including SD. Toxicity was less than reported for higher dose regimens or low dose aminoglutethimide without hydrocortisone, particularly nausea and drowsiness. Survival from first relapse and start of therapy was not significantly different between PR and SD. This dosage regimen appears of comparable efficacy to previously reported higher dosage regimens with reduced toxicity compared to low dose regimens without hydrocortisone.

Aged↗
PubMed1989

Antibiotics and nephrostomy tube care: preliminary observations. Part I. Bacteriuria.

The authors sought to establish whether bacteriuria or candiduria would develop in patients with a noninfected, obstructed renal collecting system after placement of a percutaneous nephrostomy tube. Tubes were placed in 27 sterile systems in 25 patients. Urine was cultured at 7-10-day intervals, and urinalysis was performed. Bacteriuria and pyuria were defined on the basis of laboratory values of greater than or equal to 10(4) colony-forming units per milliliter and greater than or equal to five white blood cells per high-powered field, respectively. Twenty-two systems were followed until all demonstrated multiple organisms. No clinical symptoms were related to bacteriuria.

Adult↗
PubMed1989

Antibiotics and nephrostomy tube care: preliminary observations. Part II. Bacteremia.

Bacteriuria occurs after long-term drainage of the kidney. This study was designed to determine if the risk of bacteremia increases at the time of tube or stent change, whether bacteremia correlates with clinical infection, and if prophylactic antibiotics are effective in the prevention of bacteremia. One hundred four tube changes in 74 patients with percutaneous nephrostomy tubes and documented positive urine cultures were studied. Patients were arbitrarily divided into groups receiving and not receiving antibiotics before nephrostomy tube change. Asymptomatic bacteremia was documented in 11 of 104 tube changes (11%). Results of five blood cultures were positive in the group receiving antibiotics, and six cases of bacteremia occurred in the group not receiving antibiotics (P = .96). Routine nephrostomy/stent change can cause frequent, asymptomatic bacteremia in patients with colonization of bacteria in the urinary tract. Antibiotic prophylaxis was unsuccessful in preventing transient bacteremia, a factor that may have implications in patients with underlying valvular heart disease and other patients at risk for bacteremia.

Adult↗