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Biomedical subjects

S Johnson

Publications and source records attributed to S Johnson.

At least 325 records · Page 18Linked to original sources

The postingestive consequences of fat condition preferences for flavors associated with high dietary fat.

To investigate whether children acquire conditioned preferences for flavors associated with high dietary fat content, 27 3- and 4-year-old children participated in a series of 12 conditioning or mere exposure sessions. Following an overnight fast, children who participated in conditioning trials consumed fixed quantities of a flavored yogurt drink that on half the days was high in fat and energy (954 kJ, 18 g fat/150 g serving) or contained no fat (277 kJ, 0 g fat/150 g serving). Children in the conditioning group consumed 150 g servings, children in the mere exposure group tasted 16 g or less of these same stimuli. Preferences were assessed before and after conditioning when the children were hungry and also postconditioning when the children were satiated. Results provided evidence for conditioned preferences based on the postingestive consequences of dietary fat. Children in the conditioning group learned to prefer the high-density paired flavor over the low-density paired flavor, and increased their preference for the high-density paired flavor from pre- to postconditioning. Children in the mere exposure group showed positive shifts in preference for both the fat-free and the high-fat paired flavors. In the conditioning group, preferences for the high-fat flavor was depressed by satiety, whereas the preference of the mere exposure group did not vary with hunger state. Conditioned flavor preferences, based on the postingestive consequences of fat intake, may contribute to children's preferences for foods high in dietary fat.

Association Learning↗

Clinical features of inflammatory dermatoses in human immunodeficiency virus type 1 disease and their correlation with Walter Reed stage. Military Medical Consortium for Applied Retroviral Research.

BACKGROUND: As part of a military study of the natural history of human immunodeficiency virus type 1 (HIV-1) disease, all patients entered in the study were examined for cutaneous changes associated with HIV-1 infection. OBJECTIVE: Our purpose was to characterize and record the types of inflammatory dermatoses in a large number of HIV-1-infected patients to determine whether there was a correlation with the stage of disease. METHODS: The clinical findings in each case were compared with the results of cultures and biopsy specimens and correlated with Walter Reed stage. RESULTS: Most of the inflammatory dermatoses were maculopapular eruptions often with prominent follicular involvement, and in some there was a lichenoid component. With increasing Walter Reed stage, many eruptions become papulosquamous, some with psoriasiform scale and some with a hypertrophic lichenoid appearance. CONCLUSION: Although most of the inflammatory eruptions were nonspecific clinically, most cases showed features resembling those in graft-versus-host disease.

Acquired Immunodeficiency Syndrome↗

Triterpenoid saponins from Gouania lupuloides.

The stems of Jamaican chawstick, Gouania lupuloides, have yielded two novel 16,17-seco-dammaranoid saponins, designated gouanoside A [4] and gouanoside B [5]. Structural assignments are based on spectroscopic data including 2D nmr experiments on the corresponding aglycones, gouanogenin A [1] and gouanogenin B [3].

Hydrolysis↗

Preattentive processing of object size: implications for theories of size perception.

Information about the visual angle size of objects is important for maintaining object constancy with variations in viewing distance. Although human observers are quite accurate at judging spatial separations (or cross-sectional size), they are prone to error when there are other spans nearby, as in classical illusions such as the Müller-Lyer illusion. It is possible to reconcile these aspects of size perception by assuming that the size domain is sampled sparsely. It was shown by means of a visual search procedure that the size of objects is processed preattentively and in parallel across the visual field. It was demonstrated that an object's size, rather than its boundary curvature or spatial-frequency content, provides the basis for parallel visual search. It was also shown that texture borders could be substituted for luminance borders, indicating that object boundaries at the relevant spatial scale provide the input to size perception. Parallel processing imposes a severe computational constraint which provides support for the assumption of sparse sampling. An economical model based on several broadly tuned layers of size detectors is proposed to account for the parallel extraction of size, the Weberian behaviour of size discrimination, and the occurrence of strong interference effects in the size domain.

Attention↗

Agrobacterium infections in humans: experience at one hospital and review.

Agrobacteria are noted primarily for their phytopathogenicity and when isolated from human clinical specimens are often considered contaminants or organisms of low pathogenicity. We report six cases at one hospital over a 6 1/2-year period in which infection was accompanied by a compatible clinical syndrome and review 19 cases reported in the literature. Fourteen of the 25 combined cases involved central venous catheter-associated infections. Six cases involved peritonitis, five of which occurred in patients undergoing continuous ambulatory peritoneal dialysis. Additional infections included two non-catheter-associated bacteremias, one prosthetic valve endocarditis, and two urinary tract infections. Most infections were community acquired, and restriction enzyme analysis of Agrobacterium isolates from eight patients at one hospital revealed unique patterns in each case without evidence for clonal dissemination of these strains. Agrobacterium isolates may be resistant to multiple antibiotics, and optimal therapy has not yet been determined. Agrobacteria should be recognized as opportunistic pathogens in the immunocompromised host, particularly in those with indwelling plastic catheters.

Adolescent↗

Purification and characterization from tobacco (Nicotiana tabacum) leaves of six small, wound-inducible, proteinase isoinhibitors of the potato inhibitor II family.

Six small molecular mass, wound-inducible trypsin and chymotrypsin inhibitor proteins from tobacco (Nicotiana tabacum) leaves were isolated to homogeneity. The isoinhibitors, cumulatively called tobacco trypsin inhibitor (TTI), have molecular masses of approximately 5500 to 5800 D, calculated from gel filtration analysis and amino acid content. The amino acid sequence of the entire 53 residues of one isoinhibitor, TTI-1, and the sequence of 36 amino acid residues from the N terminus of a second isoinhibitor, TTI-5, were determined. The two isoinhibitors differ only at residue 11, which is threonine in TTI-1 and lysine in TTI-5. The isoinhibitors are members of the potato inhibitor II family and show considerable identity with the small molecular mass members of this family, which include the eggplant inhibitor, two small molecular mass trypsin and chymotrypsin inhibitors from potatoes, and an inhibitor from pistils of the ornamental plant Nicotiana alata. Antibodies produced against the isoinhibitors in rabbits were used in radial immunoassays to quantify both the systemic wound inducibility of TTI in tobacco leaves and its constitutive levels in flowers.

Amino Acid Sequence↗

Development of a rapid and efficient restriction endonuclease analysis typing system for Clostridium difficile and correlation with other typing systems.

A HindIII restriction endonuclease analysis (REA) typing system for total genomic Clostridium difficile DNA including a rapid and efficient method of DNA extraction and a scheme for organizing unique electrophoretic DNA band patterns was developed. REA typing was performed by two extraction methods for 1,965 C. difficile isolates obtained from patients with symptomatic C. difficile disease, asymptomatic patients who were C. difficile culture positive, and environmental surfaces. This isolate collection yielded 206 unique REA types, which were organized into 75 groups. A reference strain representing each unique REA type was chosen for DNA band pattern comparisons, cytotoxin testing, and plasmid analysis. The DNA band patterns utilizing a guanidine thiocyanate-EDTA-Sarkosyl DNA extraction method were 94% reproducible, while the original and sporadically problematic diethyl pyrocarbonate-sodium dodecyl sulfate DNA extraction method was 98% reproducible when readable patterns were obtained. Reference strains from 43 of the 75 groups were cytotoxin positive, 28 groups were cytotoxin negative, and 4 groups included both toxigenic and nontoxigenic strains. Cytotoxicity of isolates with a particular REA type was always consistent with the toxicity of the reference strain for that type. REA typing was able to discriminate strain differences within types identified by the immunoblot (89 isolates), bacteriophage-bacteriocin (44 isolates), and ribotyping (23 isolates) methods. REA typing is a sensitive, discriminating, reproducible, and rapid method for differentiating C. difficile strains and is suitable for large-scale epidemiologic studies.

Bacterial Typing Techniques↗

Apocrine metaplasia: a new type of müllerian metaplasia.

Apocrine differentiation was an incidental finding in an ovarian cyst. This is considered to be a further example of Müllerian metaplasia that has not been described before and which, theoretically, could occur in any organ of Müllerian derivation (ovary, uterus, cervix or fallopian tube). It is suggested that sites of such metaplasia could in turn be the origin of primary apocrine carcinoma in any of the above locations.

Apocrine Glands↗

Prevalence of chronic fatigue syndrome-related symptoms among nurses.

Chronic Fatigue Syndrome is an illness that is characterized by debilitating fatigue and a group of other related symptoms. Few epidemiological studies have been conducted, and none have focused on a nursing population. The present study is the first to assess the prevalence of Chronic Fatigue Syndrome-related symptoms in a sample of nurses. Demographic characteristics, symptoms, and possible prevalence rates are presented and discussed. When using both narrow and more inclusive criteria to define this symptom complex, higher rates of this disorder were found than in previous epidemiological studies. The implications of these findings are discussed.

Adult↗

The effects on rat thyroid function of an hepatic microsomal enzyme inducer.

1. Following daily administration to male albino rats for 2 weeks, beta-naphthoflavone (25 and 60 mg kg-1, i.p.) and phenobarbitone (100 mg kg-1, p.o.) produced their characteristic patterns of induction of P450-related enzyme activities. beta-naphthoflavone also induced p-nitrophenol glucuronidation by 160% over controls, while phenobarbitone produced only a 45% induction of this conjugation activity. 2. beta-Naphthoflavone produced significant reductions in plasma thyroxine (T4) concentrations on days 4 and 16 and also decreased tri-iodothyronine (T3) on day 4. Thyroid-stimulating hormone (TSH) was significantly increased on day 16 by the higher dose of beta-naphthoflavone. Thyroid weight was significantly increased at both dose levels on day 16 and liver weight was significantly increased on both days 4 and 16. No histopathological changes were seen in the liver or pituitary, but 30% of the animals showed minimal to mild follicular epithelial hypertrophy of the thyroid gland. 3. Phenobarbitone had no effect on T4 concentrations, but significantly decreased T3 on day 4. TSH increased by 60% on day 16, but was not statistically significantly compared with controls. Thyroid weight was significantly increased on day 16 and liver weight was significantly increased on days 4 and 16. Mild to moderate thyroid follicular epithelial hypertrophy and moderate hepatocyte hypertrophy occurred in all animals. No histopathological changes were seen in the pituitary. 4. The early changes in T4 and/or T3 were probably due to increased hepatic clearance by induction of thyroxine glucuronidation with both compounds. Thyroid hypertrophy would be expected to follow as a result of activation of the hypothalamic-pituitary-thyroid axis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Reliability and validity data for a Chinese translation of the Center for Epidemiological Studies-Depression.

A translated version of the CES-Depression scale attained a reliability coefficient alpha of 0.92 in a group of 30 adult Chinese persons with noninsulin-dependent diabetes mellitus. Fifteen percent of the sample scored 16 or above, which has been noted as indicative of depression in U.S. samples. The validity of the instrument was assessed through an in-depth content analysis and through convergent validity analyses. Comparison of depression scores of this sample with those from English-speaking Occidentals shows that diabetes disease-related factors may be an important influence on depression.

Aged↗

Boozing, sniffing, and toking: an overview of the past, present, and future of substance use by American Indians.

This paper provides an overview of Indian peoples, alcohol misuse, and the prevalence of drug and inhalant experience. Early use of alcohol among North American Native peoples may represent early chemical warfare to gain European advantage over an "enemy." The magnitude of the present-day problem of alcohol and substance misuse is described in mortality rates and proportionate use reports. The use of other drugs and substances, such as inhalants, amphetamines, sedatives, and hallucinogens is examined. A brief overview of the history and complex relationships between American Indians and alcohol from the time of initial contact to the present is sketched out before approaches to primary, secondary and tertiary prevention are considered. The issue of potential conflict between tribal statutes and health objectives is noted. Some possible solutions are proposed.

Age of Onset↗

Primary and secondary infection with human parvovirus B19 in pregnant women in South Africa.

A study of human parvovirus B19 infection in 1,967 pregnant women of all races in Johannesburg revealed an overall prevalence of 24.9% for IgG antibodies and 3.3% for IgM antibodies. Of the 64 IgM-positive sera indicating active infection, 62 were resistant to urea denaturation. No differences in the prevalence of IgG antibodies between population groups were observed, but active infections, as demonstrated by IgM antibodies, were significantly more prevalent in black than in white, coloured or Asian mothers.

Antibodies, Viral↗

Hepatitis B virus prevalence in two institutions for the mentally handicapped.

A comparative study of the prevalence of hepatitis B virus infection in two institutions for the mentally handicapped was carried out between April and November 1989 and April and August 1991. The institutions were situated within 10 km of each other in north-eastern Johannesburg. One institution had a significantly higher prevalence of virus markers, 68% (139 of 203) compared with 23% (40 of 176), was in poorer condition and had more severely handicapped residents with more aggressive behaviour. However, the most important difference between the two institutions was that residents at the higher-prevalence institution were admitted at a considerably younger age. Younger individuals appear to be more susceptible to infection and are more likely to develop persistent infection, thus contributing to a greater pool of infection in the institution.

Adolescent↗

Is antenatal screening for rubella and cytomegalovirus justified?

Altogether 2,250 asymptomatic pregnant women attending an antenatal clinic were investigated for serological evidence of past exposure to rubella and cytomegalovirus (CMV) as well as for active primary infection or reinfection/reactivation. Only 7 (0.3%) active rubella infections were diagnosed, none of them primary. Similarly, out of 132 patients with active CMV, only 5 primary infections (3.8%) were diagnosed; the vast majority--127 (96%)--had reactivation infections. No congenital rubella infections were detected, while the transplacental transmission rate for CMV was 6.4%. None of the infants followed up was clinically affected at birth or at 6 months. No racial differences in seroprevalences for CMV or rubella immunoglobulin were observed, but immunoglobulin antibody prevalence to CMV was significantly lower in the white group. From this study there appeared to be no indication for routine antenatal screening for CMV in asymptomatic mothers.

Carrier State↗

Should pregnant urban south African women be screened for hepatitis B?

The prevalence of hepatitis B virus (HBV) infection in the South African urban obstetric population, which consists of white, black, coloured and Asian patients from different socio-economic, cultural and geographical backgrounds, is unknown. Routine screening performed in 3,469 urban pregnant women revealed that 42 patients were HBV surface antigen-positive (a prevalence of 1.21%). Only 2 patients (4.6%) were hepatitis B e antigen (HBeAg)-positive (0.06% of the entire cohort), whereas the remaining 40 were identified as hepatitis B e antibody-positive. Despite a significant increase in the numbers of black patients, there has not been an accompanying increase in the number of HBV carriers. Replicative infection was equally distributed among white and black pregnant women. Because the low prevalence of HBeAg results in lack of perinatal transmission and the prevention of a single case of neonatal hepatitis B infection is costly, we conclude that in South African urban hospitals, routine screening for hepatitis B is not cost-effective.

Carrier State↗