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Biomedical subjects

A M Smith

Publications and source records attributed to A M Smith.

At least 199 records · Page 11Linked to original sources
PubMed1996

High schoolers masturbatory practices: their relationship to sexual intercourse and personal characteristics.

This study examined the self-reported masturbatory experiences of high schooler and the relationships between masturbation and sexual intercourse and personal characteristics of these young people. A total of 436 suburban Australian adolescents between 15 and 18 years of age participated. Boys were more likely to report ever having masturbated (58.5%, versus 42.7%) and to have done so more frequently than girls (38.2% versus 8.7% reporting masturbating three or more times a week). While there was no significant sex difference in the age of initiation of masturbation there was some evidence that girls began masturbation earlier than boys. Whether sexual intercourse replaced or supplemented masturbation as a sexual practice could not be resolved, but there was evidence that masturbation was positively correlated with sexual self esteem. Young people whose parents provided a more open environment for the discussion of sexuality were more likely to report having masturbated, although the environment had a complex relationship with masturbatory practices as did young people's self rated physical maturity compared to their peers. A range of social and contextual factors must be explored to understand more fully this important component of young people's sexual experience.

Adolescent↗
PubMed1996

Audit on the use of prophylactic parenteral antimicrobial agents and the use of co-amoxiclav and metronidazole.

UNLABELLED: Following the recommendations of a previous audit, specific objectives were chosen for reaudit. The aim was to measure the adherence to agreed protocols for the use of prophylactic antimicrobial agents; including the use of the once only part of the Kardex and to measure the adherence to protocols for the use of parenteral co-amoxiclav and metronidazole. The audit was conducted in the same hospital as the original study. Data was collected for one month on all patients receiving prophylactic antimicrobial agents, parenteral co-amoxiclav or metronidazole. A microbiologist assessed the compliance to the agreed written protocols, which had been distributed and explained to each resident. One hundred and eighty-eight patients received 226 antimicrobial courses (649 doses). Seventy-two per cent of courses were considered appropriate compared with 65% in 1993. The criteria for this audit only allowed one cephalosporin choice per directorate and accounted for the inappropriateness of choice to be 19% compared with 12% in 1993. This was confined to one directorate and an overall improvement of 79% would have been achieved if any cephalosporin could be chosen as 1993. Eighty-two per cent of doses were considered appropriate if written in the once only part of the Kardex or the anaesthetic sheet compared with 51% of those written in the general part. Only nine per cent of courses were too long compared with 16% in 1993. Fifty seven patients were given 125 days of co-amoxiclav, 94 days for treatment and 31 days for prophylaxis. Co-amoxiclav use overall was 33% less than 1993 with an improvement of appropriateness from 30% to 68%. CONCLUSIONS: An overall improvement in the appropriateness of prophylactic antibiotic use was achieved by the implementation of agreed protocols. An automatic stopping system reduced the continuation of prophylaxis.

Amoxicillin↗
PubMed1995

A prospective follow-up study of brain morphology and cognition in first-episode schizophrenic patients: preliminary findings.

Brain morphological abnormalities have been reported in several independent investigations of chronic schizophrenic patients. The present study is a prospective 4-year follow-up of first-episode schizophrenic patients to determine whether some of these abnormalities may be a consequence of regional brain structural change over time after the onset of a first psychotic episode. Whole hemisphere, temporal lobes, superior temporal gyrus, hippocampus, caudate, corpus callosum, and lateral ventricles were measured in a series of MRI scans taken over a 4-year period in 20 patients and five controls. Total volume reduction was noted in both hemispheres to a greater degree in patients than controls. When adjusted for total brain size, left ventricular enlargement occurred in patients, but not controls, over time. These preliminary data suggest that subtle cortical atrophy may be occurring over time after the onset of illness.

Adult↗
PubMed1995

In multiple myeloma, clonotypic B lymphocytes are detectable among CD19+ peripheral blood cells expressing CD38, CD56, and monotypic Ig light chain.

Multiple myeloma (MM) is characterized by a plasma cell infiltrate of the bone marrow (BM). However, late-stage monotypic B cells have been detected in the blood. This work analyzes the effects of clinical treatment on late stage CD19+ B cells present in 752 blood samples from 152 MM patients. MM patients have 2 to 8 times as many circulating CD19+ cells as do normal donors. Analysis of the Ig heavy chain (IgH) gene rearrangements using polymerase chain reaction indicates that the CD19+ population includes cells sharing the same clonotypic CDR3 region as is detected in the BM plasma cells, for patients analyzed during chemotherapy or in relapse. They are also monotypic as defined by their cytoplasmic or surface expression of Ig kappa or lambda light chain. The light chain restriction is the same as that of the BM plasma cells. Individual patients observed over 1- to 2-year periods exhibit considerable variation in the number of B cells present in blood; this number does not correlate with the concentration of serum monoclonal Ig. The monoclonal blood CD19+ cells are not eliminated by any of the chemotherapy regimens analyzed and remain at high levels during transient remissions. Patients in the progressive phase of disease or in relapse have significantly higher numbers of B cells than do patients in transient remission or untreated patients. During periods when the quantity of blood B cells approaches normal, phenotypically their quality is highly abnormal, with physical and phenotypic heterogeneity. Most B cells express CD45R0, a high density of CD38, and CD56 characteristic of late-stage B or pre-plasma cells. CD38hi blood B cells had a cyclical presence. We conclude that monoclonal B cells in the blood of myeloma patient populations include drug-resistant reservoirs of clonotypic cells that may underlie relapse.

ADP-ribosyl Cyclase↗
PubMed1995

Digestion of haemoglobin by schistosomes: 35 years on.

Adult schistosomes obtain nutrients by digesting haemoglobin, which they obtain from ingested host red blood cells. Here John Dalton, Angela Smith, Karen Clough and Paul Brindley argue that a cathepsin L proteinase recently identified in their laboratory as the predominant cysteine proteinase activity of Schistosoma mansoni may play the leading role in haemoglobin digestion. They discuss the importance of elucidating the roles of both cathepsin B and cathepsin L in the digestion of haemoglobin, since both should be considered important targets to which novel schistosomicidal agents could be directed.

Journal Article↗
PubMed1995

A bolus for the administration to cattle of metacercariae of the liver fluke Fasciola hepatica.

A gelatin-agar bolus, designed and developed for the administration of metacercariae of the liver fluke Fasciola hepatica, was evaluated in adult Holstein Friesian cattle. The metacercariae, enclosed within a gelatin capsule, were placed inside the bolus and delivered to each animal using an oesophageal balling gun. At slaughter, 13 weeks after challenge, an average of 25% of the challenge dose was recovered from each liver. This percentage recovery is similar to that obtained with other known methods. The new bolus, however, offers improved handling qualities. In addition, the bolus also has potential for improving a number of other techniques including those for the administration of other parasites, compounds or chemotherapeutic agents.

Agar↗
PubMed1995

Starch branching enzymes belonging to distinct enzyme families are differentially expressed during pea embryo development.

cDNA clones for two isoforms of starch branching enzyme (SBEI and SBEII) have been isolated from pea embryos and sequenced. The deduced amino acid sequences of pea SBEI and SBEII are closely related to starch branching enzymes of maize, rice, potato and cassava and a number of glycogen branching enzymes from yeast, mammals and several prokaryotic species. In comparison with SBEI, the deduced amino acid sequence of SBEII lacks a flexible domain at the N-terminus of the mature protein. This domain is also present in maize SBEII and rice SBEIII and resembles one previously reported for pea granule-bound starch synthase II (GBSSII). However, in each case it is missing from the other isoform of SBE from the same species. On the basis of this structural feature (which exists in some isoforms from both monocots and dicots) and other differences in sequence, SBEs from plants may be divided into two distinct enzyme families. There is strong evidence from our own and other work that the amylopectin products of the enzymes from these two families are qualitatively different. Pea SBEI and SBEII are differentially expressed during embryo development. SBEI is relatively highly expressed in young embryos whilst maximum expression of SBEII occurs in older embryos. The differential expression of isoforms which have distinct catalytic properties means that the contribution of each SBE isoform to starch biosynthesis changes during embryo development. Qualitative measurement of amylopectin from developing and maturing embryos confirms that the nature of amylopectin changes during pea embryo development and that this correlates with the differential expression of SBE isoforms.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1995

Biochemical and molecular characterization of a novel starch synthase from potato tubers.

An isoform of starch synthase from potato tubers which is present both in the stroma of the plastid and tightly bound to starch granules has been identified biochemically and a cDNA has been isolated. The protein encoded by the cDNA is 79.9 kDa and has a putative transit peptide and a distinct N-terminal domain which is predicted to be highly flexible. It is similar in both amino acid sequence and predicted structure to the granule-bound starch synthase II (GBSSII) of pea embryos. When expressed in Escherichia coli, the mature protein has starch synthase activity. The importance of the isoform has been assessed by biochemical measurements and antisense transformation experiments in which the amount of the isoform in the tuber is severely and specifically reduced. Both approaches indicate that the isoform contributes a maximum of 15% of the total starch synthase activity of the tuber. It is suggested that this isoform and the GBSSII of pea embryos represent a widely distributed class of isoforms of starch synthase. The contribution to total starch synthase activity of members of this class probably varies considerably from one type of storage organ to another.

Amino Acid Sequence↗
PubMed1995

Insulin, but not estrogen, correlated with indexes of desaturase function in obese women.

This study determined the associations of serum insulin and estrogen with fatty acid composition, fatty acid product/substrate ratios used as indexes of desaturase enzyme function, and platelet aggregation in obese and lean women. Thirty women were classified as obese (n = 8) or lean (n = 21) based on body mass index. Obese women were characterized by higher insulin levels (p < 0.05) but fasting glucose levels did not differ (p > 0.05) from lean women. Insulin positively correlated with increased C20:4n6/C18:3n6 (index of delta 5-desaturase) (p < 0.05) and C20:4n6/C18:2n6 (index of overall n6 pathway activity) (p < 0.01) in serum, and the n5 pathway in platelets (p < 0.01), but there was no correlation for insulin with platelet C18:3n6/C18:2n6 (index of delta 6-desaturase activity). Insulin was also positively related (p < 0.01) to aggregation as measured by impedance and negatively related to lag time (p < 0.05). Platelets of obese women aggregated more (p < 0.05) compared to lean women and began aggregating faster (p < 0.05), suggesting the possibility that the obese women were at greater risk for enhanced blood clotting. Plasma estrogen was correlated with age (p < 0.05) but not for other variables studied (p > 0.05). Insulin, but not estrogen, appears to influence desaturase activity, as demonstrated by increased desaturase function associated with hyperinsulinemia in obese women.

Adult↗
PubMed1995

Selenate fortification improves selenium status of term infants fed soy formula.

Thirty-three healthy term infants were fed either soy formula (SF, 0.028 mumol Se/L; n = 17) or soy formula with added selenate (SF+Se, 0.17 mumol Se/L; n = 16) from birth (+4 d) to 16 wk. Selenium intakes of infants fed SF+Se were similar to the recommended dietary allowance and significantly greater than those of SF-fed infants. The SF group had significantly lower plasma, erythrocyte, and urine selenium, and lower plasma and erythrocyte glutathione peroxidase (GPx) activities at 16 wk compared to those of infants fed SF+Se. A decrease in plasma selenium was observed in SF-fed infants, whereas no differences in plasma selenium were found in infants fed SF+Se. These results indicate that selenate added to soy formula is highly available and effective at maintaining infant plasma and erythrocyte selenium concentrations and GPx activities that are greater than those of infants fed soy formula not fortified with selenium.

Double-Blind Method↗
PubMed1995

Dietary behaviours of volunteers for a nutrition education program, compared with a population sample.

The dietary behaviours of and recent dietary change by volunteers for a nutrition education program were compared with those of a more population-representative sample. The population sample was randomly selected from the electoral rolls of three Australian cities. Those selected received questionnaires which were to be completed and returned by mail. The sample of volunteers was recruited from the electoral rolls of suburbs of either high or low social status in one of these cities. Volunteers were posted a questionnaire, to be returned in person. A quantified food frequency questionnaire was used to estimate relative intake of 19 nutrients, plus energy intake. Occupation, age, sex, reported recent dietary change and diet-related beliefs were also assessed. The population sample was weighted to the age and occupational distribution of the education program sample. Compared to the 874 respondents in the population sample (70.4 per cent response rate), the 487 volunteers (24.2 per cent response rate) for the nutrition education program had healthier nutrient intakes and reported more dietary behaviour changes. Recruitment in the education program was greater in areas of higher social status (32 per cent) than in areas of lower social status (20 per cent). The potential effect of such a program on the whole population was demonstrated by the proportions that volunteered and the characteristics of these volunteers. The need to provide a range of opportunities for changing dietary behaviour, according to the health-related behaviours and beliefs of target groups and their socio-economic circumstances, was highlighted.

Adolescent↗
PubMed1995

Use of hormone replacement therapy by Melbourne women.

Hormone replacement therapy (HRT) is used for relief of symptoms related to the menopause and for the prevention of postmenopausal osteoporosis and cardiovascular disease. Patterns of use of HRT are thought to be changing rapidly, but little is known about who is using the therapy, for what purpose or for what period of time. Telephone interviews were conducted in May 1991 with a randomly selected sample of 2001 Australian-born women aged 45 to 55 years living in Melbourne, as part of the Melbourne Women's Midlife Health Project. Questions related to use of HRT, health status, use of health services, sexual functioning, attitudes to menopause and aging, and sociodemographic characteristics. Twenty-one per cent of the sample were using HRT. Use was more prevalent among women 50 years and over (28 per cent) than those under 50 (15 per cent). Seventeen per cent of nonhysterectomised women, 31 per cent of hysterectomised women and 49 per cent of women who had undergone hysterectomy and bilateral oophorectomy were current users. Almost 60 per cent had been using the therapy for two years or less, and 34 per cent for one year or less. Just over half reported control of hot flushes as a benefit, and 10 per cent mentioned prevention of bone loss as a benefit. Logistic regression analysis identified differences between users and nonusers in experience of hot flushes, health status, use of preventive and treatment services, sexual functioning, wellbeing, attitudes to menopause and aging, and sociodemographic characteristics. These differences may relate to risk of later cardiovascular disease.

Age Factors↗
PubMed1995

An investigation of the effect of finite system resolution and photon noise on the bias and precision of dynamic cardiac SPECT parameters.

The exchange of a radionuclide (and similarly of oxygen) between blood and the myocardium is a dynamic process. Dynamic SPECT offers the possibility of directly quantifying the kinetic parameters which describe this process. In this paper we investigate and quantify the effect of typical SPECT system resolution and photon counting statistics on the bias and precision of dynamic cardiac SPECT parameters. System resolution and photon noise are only two of the image degrading processes which occur in SPECT. Therefore, the bias and precision quoted should be viewed as a lower limit on those which could be expected with an experimental study. Dynamic SPECT projection data are simulated using a realistic human torso phantom. Data are simulated assuming both perfect system resolution and a system resolution typical of a clinical SPECT system. A triple detector SPECT system which acquires a full set of projection data in 10 s using continuous detector motion is modelled. Kinetic parameters are estimated using a number of myocardial regions of interest. The results show that the rate constant characterizing the washing of activity into the myocardium is more sensitive to region of interest position than is the washout rate constant. The bias and precision of the dynamic parameters are estimated from multiple realizations of projection data exhibiting various noise levels. The main effect of increased photon noise in the projection data is to decrease the precision of the estimated parameters. However, there is also some evidence that for high noise levels the bias of the parameters may also be affected.

Biophysical Phenomena↗
PubMed1995

Alterations in penicillin-binding protein 2B from penicillin-resistant wild-type strains of Streptococcus pneumoniae.

The 1.5-kb transpeptidase-encoding region (TER) of penicillin-binding protein (PBP) 2B was amplified and sequenced from 18 penicillin-resistant isolates of Streptococcus pneumoniae, with each isolate representing a different DNA fingerprint profile of the TER. PBP 2B TERs from penicillin-resistant isolates revealed extensive sequence divergence from the penicillin-susceptible R6 strain, differing by up to 170 nucleotide substitutions and resulting in up to 38 alterations in the amino acid sequence of the protein. All penicillin-resistant isolates showed sequence divergence within a +/- 300-bp area at the center of the PBP 2B TER. Although a number of amino acid substitutions were found within this central area of PBP 2B, only two substitutions were common to all resistant isolates, namely, Thr-252 replacement by Ala and Glu-282 replacement by Gly. These two substitutions appear to be essentially associated with a decreased affinity of PBP 2B for penicillin. A second block of divergent nucleotide sequence was prominent amongst isolates with high levels of resistance. This was a +/- 100-bp area of the TER around nucleotide 1300 and included the substitution of Gly for Asp-431, which was the only amino acid substitution within this area that was common to all isolates. These data may assist in the definition of the structural changes in the penicillin-binding site of PBP 2B associated with penicillin resistance in S. pneumoniae.

Amino Acid Sequence↗
PubMed1995

EMG analysis of harmaline-induced tremor in normal and three strains of mutant mice with Purkinje cell degeneration and the role of the inferior olive.

1. The effects of intraperitoneal injections of 10 mg/kg harmaline were tested in normal mice and three strains of cerebellar mutant mice with Purkinje cell degeneration. Ten normal (wild-type) mice (+/+), as well as five lurcher (lc/+), six nervous (nr/nr), and eight Purkinje cell degeneration (pcd/pcd) mutants were implanted with chronic electromyogram (EMG) electrodes in the hamstring and quadriceps muscle groups of the right hindlimb. 2. EMGs were recorded in each of the mice during spontaneous activity before and after intraperitoneal injections of 0.3 ml harmaline (10 mg/kg). Spectral analysis was used to quantify the amplitude and frequency of tremor found in the EMGs after harmaline administration. Normal mice responded to harmaline with strong, continuous 11- to 14-Hz tremor. Mutants from the pcd/pcd strain also reacted with continuous tremor, but of lower amplitude and frequency. In contrast, nr/nr mutants exhibited intermittent paroxysmal tremor lasting for only a few seconds, and lc/+ mutants showed no evidence of tremor whatsoever. 3. In order to detect covert tremor that was possibly not revealed by focal intramuscular EMG recordings, several mutant and normal mice were also tested on a suspended platform to which an accelerometer was attached. The results confirmed the findings from EMG recordings. 4. An incidental observation made during the course of this study was that harmaline tremor disappeared from the normal mouse during swimming and reappeared when the animal was withdrawn from the water. 5. Although Purkinje cells appeared to increase both the depth of modulation and the frequency of tremor, the inhibitory action of the cerebellar cortex does not seem to be essential for the generation of tremor. 6. Parasagittal cerebellar sections of the normal, wild-type mice and the three strains of cerebellar mutant mice of various ages were stained with cresyl violet and examined for Purkinje cell degeneration. Purkinje cell degeneration was found to be complete in the pcd/pcd and lc/+ strains. Although an initial examination of parasagittal sections of the nr/nr strain failed to find any surviving Purkinje cells, further examination of sections cut in the coronal plane revealed small clusters of Purkinje cells in the vermal area of the posterior lobe. 7. The retrograde transport of wheat-germ-agglutinin-conjugated horseradish peroxidase (WGA-HRP) pressure-injected into the cerebellar cortex was used to study the olivocerebellar projections in the wild-type mice and the three strains of cerebellar mutant mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗