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Biomedical subjects

R Joseph

Publications and source records attributed to R Joseph.

At least 181 records · Page 10Linked to original sources
PubMed1984

An evaluation of tamoxifen as a partial agonist by classical receptor theory--an explanation of the dual action of tamoxifen.

Tamoxifen is known to have both agonist and antagonist properties. Classical receptor theory predicts that given the relative concentrations of a partial agonist and full agonist acting on the same receptor, the partial agonist may reduce the effect of the full agonist. The immature rat uterine model is an excellent system to evaluate the interactions of estradiol and tamoxifen by application of receptor theory. Using this model, tamoxifen demonstrates both additive and antagonistic effects to estradiol in the fashion predicted by theory. The effects of tamoxifen are additive at low doses of estradiol and antagonistic over higher estradiol doses. It is possible that the dualism of agonism and antagonism seen in other target organs and species is a function of these basic characteristics of a partial agonist.

Animals↗
PubMed1984

Erythrocyte choline concentrations and cluster headache.

Erythrocyte choline concentrations were measured in patients with cluster headache and age related control subjects. Concentrations were significantly reduced in the patients with headache both during a cluster period and between clusters, being 58% and 55% of the control value, respectively. After two weeks' treatment with lithium, choline concentrations in the patients with cluster headache increased to 78 times the control value (mean 369.2 mumol/l (3840 micrograms/100 ml) compared with 4.7 mumol/l (49 micrograms/100 ml]. The presence of depressed erythrocyte choline concentrations during and between cluster attacks indicates that this may be a predisposing condition which results in a cluster attack only when associated with a trigger factor.

Adult↗
PubMed1984

Two brains, one child: interhemispheric information transfer deficits and confabulatory responding in children aged 4, 7, 10.

In an investigation of developmental trends in the ability to transfer information between the cerebral hemispheres, 138 children, ages 4, 7, and 10, viewed pictures presented to either the right or left hemisphere and were asked to describe what was viewed. Responses were socored for the number of accurate pictorial features reported (inclusion score), confabulation (erroneous embellishment), perceptual, semantic, and syntactic errors. Misses (failure to provide a response) were also noted. A preponderance of errors were found, such that 4-year olds engaged in a significant degree of confabulatory responding following right vs. left presentation. A significant inverse relationship was found between inclusion and confabulation such that the larger the gap in information reported the greater was the tendency to insert (confabulate) erroneous material. In addition, all children were given a tactile-shape recognition task employing both transfer and non-transfer conditions and requiring tactile exploration and visual recognition. Significantly more errors were found on the transfer vs. non transfer task among the 4-year olds only. In that deficits in information transfer were not complete but only partial, and given that significant intra-hemispheric (non-transfer) errors were also discovered, it was concluded that the hemispheres of children age 4 are not completely but only partially disconnected, and that intra-hemispheric (cortical) immaturity plays a significant role in the production of processing deficits.

Cerebral Cortex↗
PubMed1984

Necrotizing enterocolitis in very low birthweight infants: a four-year experience.

Fifty (13%) of 375 infants who weighed 1500 g or less at birth had necrotizing enterocolitis (NEC). Haematological changes suggestive of sepsis occurred in 83% and positive bacteriological cultures were found in 38%, the most common organism isolated being Clostridium perfringens. Complications included intestinal perforation in six patients and recurrence of NEC in five, of whom one subsequently developed an intestinal stricture. Five of the eight nursery deaths were secondary to peritonitis and overwhelming sepsis from NEC. In spite of the discontinuation of milk feeds for prolonged periods, satisfactory caloric intake and weight gain were achieved with parenteral nutrition in the survivors. Of the 41 long-term survivors, six (15%) were found to have a disability at 2 years of age, corrected for prematurity, compared with 48 (20%) of 241 very low birthweight survivors from the same study period who did not have NEC. None had evidence of gastrointestinal dysfunction. Six (15%) children remained below the 10th percentile for both weight and height. This study showed that early diagnosis and therapy for NEC in very low birthweight infants were associated with a favourable short- and long-term outcome.

Bacterial Infections↗
PubMed1984

Perinatal risk factors for necrotizing enterocolitis.

The perinatal histories of 50 very low birthweight infants weighing 1500 g, or less, with necrotizing enterocolitis were compared with those of the remaining 325 very low birthweight infants who were admitted to this hospital during a four year study period. Many factors previously reported to be associated with necrotizing enterocolitis were found with equal frequency in both groups of babies. The only adverse factor which was more frequently present in patients with necrotizing enterocolitis was hypothermia on admission to hospital. Those infants who developed severe necrotizing enterocolitis also had a higher incidence of polycythaemia. A further controlled study which examined feeding practices showed that the timing, type, and volume of milk feeding were not different in infants with necrotizing enterocolitis and matched controls. Prematurity is clearly the greatest risk factor which predisposes to the development of necrotizing enterocolitis and most of the factors previously implicated in the aetiology may simply represent the descriptive characteristics of a population of sick, very low birthweight infants.

Animals↗
PubMed1983

Single endometrial aspiration for determination of ovulation.

The possibility of utilizing a single endometrial aspiration for the determination of ovulation was explored and compared with endometrial histology, serial vaginal cytology and plasma progesterone. A total of 180 women with normal, regular cycles and no pelvic pathologic conditions were studied. A correlation of 90.5% was observed between aspiration smears and histology. Vaginal cytology and histology agreed in 71.7% of the cases, while plasma progresterone and endometrial histology correlated in 95% of the women. Endometrial aspiration appeared to be an accurate, quick, inexpensive, convenient and a one-time method, which could be repeated in successive cycles without any patient discomfort.

Endometrium↗
PubMed1982

The neuropsychology of development hemispheric laterality, limbic language, and the origin of thought.

Discussed evidence and assumptions that concern hemispheric laterality and asymmetrical functional representation. It is hypothesized that the asymmetrical linguistic-motor vs. sensory-spatial-affective representation of function may be a result of differential rates of cortical, subcortical and spinal motor-sensory maturation. Evidence with regard to embryological and early postnatal neurological development is reviewed. It is argued that motor areas mature before sensory and that the left hemisphere develops prior to the right, such that the left hemisphere gains a competitive advantage in the acquisition of motor representation, whereas the later maturing right has an advantage in the establishment of sensory-affective synaptic representation, including that of limbic mediation. The influences of these differing maturational events on cognitive and psychic functioning are examined, particularly with regard to limbic influences on the development of language, thought, and mental imagery, and the effects of early emotional experience on later behavior. Thinking is viewed in part as a left hemisphere internalization of egocentric language, the internalization of which corresponds to the increasing maturation of intra-cortical and subcortical structures and fiber pathways, and the myelination of the callosal connections that subserve information transfer between the hemispheres. It is argued that thought is a means of organizing, interpreting, and explaining impulses that arise in the non-linguistic portions of the nervous system so that the language dependent regions may achieve understanding. In addition, the neurodynamics and mechanisms involved in the mislabeling, misinterpretation, and inhibition of impulses, desires, and emotional expression are discussed in relation to disturbances in psychic functioning.

Adolescent↗
PubMed1982

Purification and properties of extracellular xylan hydrolases of Streptomyces exfoliatus.

Fractionation of extracellular xylan hydrolases of a strain of Streptomyces exfoliatus MC1 (by salting out, molecular sieving and ion exchange chromatography) revealed the presence of five species of the enzyme. Three major fractions could be purified to homogeneity; two were apparently endohydrolases and the third an exo-xylan hydrolase. The three fractions showed different degrees of affinity to the substrate and differed considerably in their substrate specificities. One of the endo-enzymes was specific to xylan while the other could also attack cellulose, inulin and pectin. The exo-enzyme showed xylanolytic and cellulolytic functions only. The three fractions further differed in their response to the presence of metal ions, mercapto reagents and compounds. Although the pH and temperature optima were different, the three fractions functioned synergistically in the hydrolysis of xylan.

Glycoside Hydrolases↗
PubMed1982

Parental age and birth order in Chinese children with congenital heart disease.

Parental age and birth order were studied in 100 Chinese children with congenital heart disease (proven by cardiac catheterisation) and in 100 controls. A higher incidence of congenital heart disease was present in the children with higher birth orders. No relationship was found between the incidence and the paternal or maternal ages. Using the method of multiple regression analysis this birth order effect was significant (p less than 0.01) and independent of parental age. This finding provides indirect evidence of environmental influence in the causation of congenital heart disease, which is known to be inherited in a multifactorial manner. Family planning to limit the size of the family may possibly contribute to the reduction of the incidence of congenital heart disease.

Adult↗
PubMed1981

Attitudes of medical students and residents toward cancer.

Attitudes toward cancer and heart disease were evaluated in 99 freshmen medical students, 76 seniors, and 66 residents using the Cancer Attitude Survey and a Semantic Differential test. The Survey revealed a rise in positive attitudes towards patients' inner resources to cope with serious illness and toward personal immortality and a rise in negative attitudes toward early diagnosis of cancer as students progressed in their training. The Semantic Differential test demonstrated more negative attitudes toward cancer than heart disease in all groups (freshman, seniors, and residents in medicine, psychiatry, or surgery). The seniors had the most positive attitudes toward cancer and freshman the least positive attitudes. The residents had more positive attitudes than the freshmen but less positive attitudes than the seniors. The residents in psychiatry had more positive attitudes than the residents in medicine, who had more positive attitudes than the residents in surgery.

Attitude of Health Personnel↗
PubMed1980

Morphological effects of monocular deprivation and recovery on the dorsal lateral geniculate nucleus in galago.

The effects of monocular lid-suture deprivation on development were evaluated by measurement of cell sizes in the lateral geniculate nuclei of six deprived and three normally reared galagos. In all animals autoradiographic demonstration of the retino-thalamic projections from one eye was used to define the lamination and distinguish the monocular from the binocular segment of the nucleus. Our results indicate that monocular deprivation significantly affects cell growth in both the binocular and monocular geniculate segments, with the greater change occurring in the binocular segment, suggesting that both visual experience and binocular competitive interactions influence geniculate cell growth in these primates. In animals forced to use their deprived eye for 2 months or more by reverse suturing, disparity of cell sizes is reduced in the monocular segment, while differences in binocular segment cell sizes are maintained. Our results also show that monocular deprivation with or without later reverse suture has an unequal influence on different geniculate layers, such that cells in laminae 4 and 5 are not as severely affected as the remaining layers. This differential influence could relate either to the unique pattern of projection of these layers to cortex or to functional differences between layers.

Animals↗
PubMed1980

Gender and early environmental influences on activity, overresponsiveness, and exploration.

One hundred eighty-five rats reared in either an enriched or restricted environment were tested during adulthood to determine the influence of gender and rearing environment on 3 related response characteristics, activity, overresponsiveness, and exploratory behavior. Eight experiments were performed. It was found that although females are more active than males, rearing environment does not influence behavior in the running wheel or open field. When tested in a complex compartmentalized open field, females in general and restricted rats are significantly more active than enriched males. In addition, over subsequent testing, restricted animals are increasingly responsive and fail to habituate to the testing stimuli. When tested and retested for maze learning ability, males excel over females; enriched rats maintain their ability to outperform restricted rats, although both groups had previously learned the problem. Moreover, enriched rats demonstrate a greater tendency to explore and make irrelevant section entries on a maze that is problem free. Restricted rats, specifically, and females generally, have difficulty suppressing a learned repetitious pattern of rewarded responding when it is subsequently punished; restricted rats were deficient in the ability to passively avoid or escape noxious stimuli. These experiments, as well as supporting evidence in the literature, indicate that rats reared in a restricted environment develop a limited behavioral repertoire which is characterized by a generalized tendency to overrespond, a propensity towards perseverating in repetitious patterns of limited and circumscribed responding, and a failure to habituate to repeated contact with novel stimuli.

Aging↗
PubMed1980

Visual deficits and recovery following monocular lid closure in a prosimian primate.

The behavioral consequences of long-term monocular lid closure in 6 deprived and 2 normal prosimian primates (Galago crassicaudatus) were examined using a visual field perimetry technique and a variety of visuomotor tests. Deprived galagos had their right lid sutured either within 8 (n = 4) or 38 (n = 2) days postpartum and were reared under these conditions for at least 8 months. Normal galagos responded briskly on all visuomotor tests including tracking, response to visual threat, ability to descend from a platform, and obstacle avoidance. Perimetry tests of these animals showed that the visual field with both eyes open was 180 degrees while each eye tested individually had a 135 degrees field. Deprived galagos tested with their experienced eye exhibited normal visuomotor behavior and normal visual fields. Following reverse suture all deprived animals behaved initially as if blind on all tests. Over the next 4-8 weeks these animals showed some limited recovery on the visuomotor tasks. Tests of perimetry indicated that by the end of four weeks of testing, vision was limited to the deprived monocular segment where it remained stable to the end of the testing period. With both eyes open, deprived galagos exhibited a normal 180 degrees visual field. Curiously, however, when stimuli were introduced simultaneously in corresponding points in both monocular segments of the field, the majority of orienting responses of deprived subjects favored the right deprived eye. Under similar testing conditions one normal subject favored its right eye and the other its left eye. The reversibility of monocular deprivation was explored further either by extending the period of forced use of the deprived eye in one animal or by removing the non-deprived eye in another animal. No further improvement in visual field perimetry was seen following a longer period of forced use of the deprived eye. In contrast, a substantial increase in the visual field could be demonstrated one month following removal of the originally experienced eye: the deprived eye field expanded to include the entire 90 degrees ipsilateral hemifield. The contralateral field of the deprived eye, however, continued to remain blind even after one year. These behavioral results suggest that although the original binocular competitive disadvantage suffered by the deprived eye during development is relatively permanent, it can partially be ameliorated by late removal of the non-deprived eye.

Animals↗