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Biomedical subjects

C Lewis

Publications and source records attributed to C Lewis.

At least 145 records · Page 8Linked to original sources
PubMed1995

Laparoscopic abdominoperineal excision of the rectum.

In laparoscopic abdominoperineal resection of the rectum (LAP-AP) an abdominal incision is completely avoided as the tumor is delivered through the perineal incision. It is our belief that the view provided in the pelvis by laparoscopy is significantly better than at laparotomy and allows excellent anatomical definition and meticulous dissection. In this study we compared the adequacy of excision of the first 12 patients undergoing LAP-AP to the last 16 patients undergoing open abdominoperineal resection (OP-AP). In all patients the procedure was carried with curative intent for adenocarcinoma and the Dukes staging and Jass score's were similar in both groups. [table: see text] The data demonstrate similar nodal harvest in both groups as well as extent of radial excision. However, two patients in the open group had microscopic radial margin involvement despite being microscopically clear at surgery. We conclude that although long-term follow-up is required to address the issue of local cancer recurrence, laparoscopic rectal dissection appears as good as open surgery and may allow a more precise assessment of excision margins.

Adult↗
PubMed1995

"Is this man your daddy?" suggestibility in children's eyewitness identification of a family member.

Studies of natural language development suggest that overextension of family memberships terms, such as daddy or papa, occurs in children in the second year of life, but rarely persists thereafter. However, in British Courts it is common for the testimony of 3- and even 4-year-olds to be dismissed on the grounds that these children may not be reliably identifying their father or stepfather when they claim that daddy was the perpetrator of abuse. This study examined whether 3-year-olds could be persuaded to confirm that a stranger who was labelled as daddy was their own father. A mock interview with experienced disclosure interviewers was conducted. Five of the 17 children--all from blue-collar families--misidentified a photograph of their own father when an identification question was repeated. Rather than undermining the validity of all preschoolers testimony, it is suggested that the responses of some children to apparently mundane questions of fact are influenced by contextual factors, including repetition of the question and the perceived omniscience of the interviewer.

Child Abuse↗
PubMed1995

Is a community-based mastoid microsuction service feasible: the audit of a pilot project.

Patients who have had a mastoidectomy form a considerable long-term follow-up commitment to their local ENT Department. A community-based mastoid aural toilet pilot project run by a GP is described using an operating microscope and suction apparatus in his surgery. To obtain the necessary information about community treatment, an audit was performed of all mastoidectomy patients from a large general practice in Portsmouth: 57 mastoidectomy patients were reviewed. During the project it was possible to transfer to the community microsuction project the long-term care of most of their mastoidectomy patients who were attending the hospital ENT outpatient clinic.

Adult↗
PubMed1995

Potential adverse effects of phytoestrogens.

Evaluation of the potential benefits and risks offered by naturally occurring plant estrogens requires investigation of their potency and sites of action when consumed at natural dietary concentrations. Our investigations have examined the effects of a range of natural dietary concentrations of the most potent plant isoflavonoid, coumestrol, using a rat model and a variety of estrogen-dependent tissues and endpoints. Treatments of immature females demonstrated agonistic action in the reproductive tract, brain, and pituitary at natural dietary concentrations. Experiments designed to test for estrogen antagonism demonstrated that coumestrol did not conform to the picture of a classic antiestrogen. However, coumestrol did suppress estrous cycles in adult females. Developmental actions were examined by neonatal exposure of pups through milk of rat dams fed a coumestrol, control, or commercial soy-based diet during the critical period of the first 10 postnatal days or throughout the 21 days of lactation. The 10-day treatment did not significantly alter adult estrous cyclicity, but the 21-day treatment produced in a persistent estrus state in coumestrol-treated females by 132 days of age. In contrast, the 10-day coumestrol treatments produced significant deficits in the sexual behavior of male offspring. These findings illustrate the broad range of actions of these natural estrogens and the variability in potency across endpoints. This variability argues for the importance of fully characterizing each phytoestrogen in terms of its sites of action, balance of agonistic and antagonistic properties, natural potency, and short-term and long-term effects.

Animals↗
PubMed1995

Sibling interaction of children with learning disabilities: a comparison of autism and Down's syndrome.

Two potentially contrasting hypotheses can be generated about sibling interactions involving a child with Down's syndrome or autism. Research on siblings would predict that learning disabled children adopt responsive roles. Studies of children with autism would predict impoverished interactions. Home observations were conducted on 30 sibling pairs involving children with autism or Down's syndrome. Both hypotheses were partially supported. All learning disabled children engaged in frequent bouts of interaction, usually directed by their sibling. While children with autism engaged in fewer bouts and imitated less, they did reciprocate their siblings' initiations. Sibling encounters provide a unique opportunity for such children to learn about social relationships.

Autistic Disorder↗
PubMed1995

Phytoestrogen influences on the development of behavior and gonadotropin function.

The effect of phytoestrogens on the sexual differentiation of gonadotropin function was examined by neonatal exposure of pups through milk of rat dams fed a coumestrol (100 micrograms/g), control, or chow diet during the "critical period" of the first 10 postnatal days or throughout the 21 days of lactation. In females, exposure to coumestrol throughout the period of lactation produced growth suppression and an acyclic condition in early adulthood resembling the premature anovulatory syndrome. When the period of treatment was restricted to the first 10 postnatal days, however, no effects on vaginal cyclicity were seen. The 10-day exposure period produced more marked effects in males, resulting in transitory reductions in body weight in weanling males and reductions in mount and ejaculation frequency and a prolongation of the latencies to mount and ejaculate. Testicular weights and plasma testosterone levels did not differ among treatment groups, suggesting that the deficits in male sexual behavior were not due to deficits in adult gonadal function. Few effects of chow treatment were observed. However, significant differences from controls were apparent for weight at vaginal opening in females, and mount rate for chow-treated males was intermediate between that of controls and that of the coumestrol-treated group. These data provide evidence that lactational exposure to phytoestrogen diets can alter neuroendocrine development in both female and male rats.

Animal Feed↗
PubMed1995

Pharmacological characterization of heterologously expressed ATP-gated cation channels (P2x purinoceptors).

cDNAs encoding P2x purinoceptors from human bladder smooth muscle and from rat PC-12 cells were expressed in oocytes and human embryonic kidney 293 cells. Agonist potencies of 2-methylthio-ATP = 2-chloro-ATP = ATP > = 2'- and 3'-O-(4-benzoylbenzoyl)-ATP > or = adenosine-5'-O-(3-thio)-triphosphate > or = P1,P5-di(adenosine-5') pentaphosphate >> ADP prevailed for both P2x purinoceptors. There were two main differences in agonist sensitivity between the two receptors. First, ATP was 10 times more potent at the receptor from bladder (EC50, 0.8 microM) than at the receptor from PC-12 cells (EC50, 8.2 microM). Second, alpha,beta-methylene-ATP and L- and D-beta,gamma-methylene-ATP were agonists in cells expressing the bladder smooth muscle receptor (EC50, 1-3 microM) but were ineffective in cells expressing the PC-12 receptor. The P2 purinoceptor antagonists suramin, pyridoxal phosphate 6-azophenyl-2',4'-disulfonic acid, and pyridoxal-5-phosphate acted similarly at both receptor forms, producing noncompetitive inhibition, with IC50 values of 1-5 microM for suramin and pyridoxal phosphate 6-azophenyl-2',4'-disulfonic acid and 10-20 microM for pyridoxal-5-phosphate. 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid distinguished receptor subtypes, producing potent inhibition of the bladder smooth muscle P2x-mediated response, with an IC50 value of 3 microM; it inhibited the PC-12 form by < 40% at 100 or 300 microM. This study thus defines the pharmacological properties of homo-oligomeric forms of these two types of cloned P2x receptor channels.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1994

Regulation of arcuate nucleus synaptology by estrogen.

Estrogen modulates the synaptology of the hypothalamic arcuate nucleus during sexual differentiation of the rat brain in both males and females. In males, testosterone of gonadal origin is converted to estrogen in the brain by an enzyme, aromatase, which is also present in females. The exposure of the male's hypothalamus to relatively high levels of estrogen (following a perinatal testosterone surge) leads to the development of a pattern of synaptogenesis which does not support an estrogen-induced gonadotrophin surge in the adult. In female rats, hypothalamic development occurs with permissively low levels of estrogen, enabling a midcycle estrogen-induced gonadotrophin surge and ovulation in adulthood. During adult reproductive life in female rats, circulating estrogen modulates the synaptology of the arcuate nucleus. The most physiological example of this is the 30-50% loss of axosomatic synapses following the preovulatory estrogen surge on diestrus-proestrus. Studies on post-synaptic membranes of the arcuate nucleus reveal sex differences in membrane organization and protein content which are estrogen-dependent. Estrogen apparently stimulates endocytosis of areas of post-synaptic membrane that are dense with small intramembranous protein particles, resulting in a reduction in the number of small intramembranous particles. This also appears to be the physiologic mechanism of neuronal changes in females during the estrus cycle. Repeated exposure to preovulatory levels of estrogen may lead to an age-related decline in reproductive capacity in female rats. Aging females lose the estrogen-induced gonadotrophin surge responsible for ovulation. This loss of function may result from a cumulative estrogen effect during the repeated ovarian cycles which results in a reorganization of the synaptology on which regulates the estrogen-induced gonadotrophin surge. The membrane organization of the senescent constant estrus aged female appears indistinguishable from the males. The hypothalamic circuits modulated by estrogen have yet to be delineated. However, recent research has shown that GABA, the monoamines, and several neuropeptides are participants in the estrogen-sensitive network which regulates GNRH secretion. In this regard, present work shows estrogen-induced changes in GABA and dopamine synapses in the arcuate nucleus.

Aging↗
PubMed1994

Audit of infection in continuous ambulatory peritoneal dialysis.

The major cause of failure of continuous ambulatory peritoneal dialysis is peritoneal or exit site infection with Staphylococcus aureus. From 1989-1992, eradication of nasal and perineal carriage, continued use of an occlusive dressing to the exit site, improved aseptic technique for dressing changes by the patient and avoidance of wetting of the dressing were used in an attempt to reduce staphylococcal infections. By comparison with the 3-year period prior to intervention, a significant increase in the life of the catheters was achieved (removed at 1 year, 13 vs. 28%, P < 0.001) with a reduction in episodes of peritonitis due to S. aureus. The study was not prospectively controlled but there did not appear to be any other factor to account for the sudden and consistent improvement observed.

Catheterization↗
PubMed1994

The prevalence of specific arithmetic difficulties and specific reading difficulties in 9- to 10-year-old boys and girls.

Data from an epidemiological sample (n = 1206) of British schoolchildren were used to estimate the proportions of 9- to 10-year-olds with specific arithmetic difficulties (SAD), combined with arithmetic-and-reading difficulties (ARD), and specific reading difficulties (SRD). Children in the sample contributed scores on separate tests of arithmetic, reading and nonverbal intelligence. Using a cutting-score approach, which took into account performance on all three tests, a small group of children with SAD (1.3%) were distinguished from larger groups with ARD (2.3%) and SRD (3.9%). Contrary to some previous reports, there were equal numbers of males and females within each of the two groups with arithmetic difficulties but a preponderance of males over females amongst the group with specific reading difficulties.

Child↗
PubMed1994

A speech rate measure of laboratory induced affect: the role of demand characteristics revisited.

The study examined the effects of mood shift on a behavioural measure to investigate an ongoing question in the mood induction literature: Whether changes in performance following laboratory based mood induction procedures reflect genuine changes in affective state, or whether such changes can be generally attributed to the demand characteristics of the experimental situation. Prior to mood induction 40 subjects were assessed on self-spaced and maximal performance articulation tasks. Following mood induction articulation rates were again recorded. It was hypothesized that while there is considerable scope for experimental demands to influence self-paced tasks, by contrast maximal performance tasks should either reduce or eliminate demand characteristics. The results indicated that maximal articulation rate was sensitive to mood induction in that performance was retarded by the depressogenic procedure and accelerated by the elation-inducing procedure. Additionally, within-subject changes in speech rates correlated with conventional self-report measures of affective state. Interestingly, the speeded task appeared more sensitive to the mood manipulation than the self-paced task where demand characteristics had been expected to exert their greatest effect. It is concluded that these results corroborate the view that laboratory based induction procedures do promote true affective change and indicate that the speeded articulation task constitutes an effective indicator of that change.

Adult↗
PubMed1994

A review of the use of chemoprotectants in cancer chemotherapy.

Dose-limiting toxicity secondary to antineoplastic chemotherapy is principally due to the inability of the drugs to differentiate between normal and malignant cells. This results in normal tissue damage, as well as the desired antitumour effect. Toxicity may be acute, as in cisplatin-induced nephrotoxicity or alkylating agent myelotoxicity and haemorrhagic cystitis, or cumulative, as in anthracycline-related cardiac toxicity or cisplatin neurotoxicity. The consequences of this often include serious adverse effects and the inability to deliver adequate dose-intensive therapy against the cancer. Chemoprotective agents have been developed to provide site-specific protection against normal tissue toxicity, without compromising antitumour activity. Several chemoprotective compounds have recently been developed, including dexrazoxane (ICRF-187), amifostine (ethiofos: WR-2721), mesna and ORG-2766. Initial results confirm their promise as selective protective agents, although further randomised trials are required to identify their optimal role when used alone or in combination with other toxicity modifiers, including haematopoietic growth factors, with the ultimate aim being adequate dose escalation of chemotherapy to overcome tumour resistance.

Adrenocorticotropic Hormone↗
PubMed1994

Skewed T-cell receptor usage and junctional heterogeneity among isletitis alpha beta and gamma delta T-cells in human IDDM [corrected].

Because of anatomical limitations, molecular characterization of islet-inflammatory T-cells in human insulin-dependent diabetes mellitus (IDDM) has remained elusive. We have isolated isletitis T-cells from pancreas graft biopsies of two patients (syngeneic and allogeneic, respectively) shortly after onset of recurrent IDDM and have characterized their repertoire by sequencing T-cell receptor (TcR)-specific cDNAs. Histopathological analysis of the grafts revealed selective beta-cell loss and isletitis characteristic of recurrent disease with no evidence of chronic inflammation or rejection. Most of the in vivo-activated isletitis T-cells were CD8+TcR alpha beta+ and CD4-CD8-TcR gamma delta+ in both patients. Comparison of the different TcR alpha,beta,gamma, and delta sequences revealed V(D)J junctional heterogeneity but skewed TcR usage within patients. Eighth of 13 different isletitis TcR beta sequences (19 of 26 cDNAs) from the syngeneic graft of patient 1 were V beta 3+, as opposed to only 1 of 31 peripheral TcR beta sequences (1 of 31 cDNAs) (61.5 vs. 3.2%, P < 0.0001). Of the 19 different isletitis TcR alpha clonotypes of this patient (24 of 42 cDNAs), 5 were V alpha 14+. The isletitis TcR beta clonotypes of the human leukocyte antigen-identical allogeneic graft of patient 2 showed selective J beta, but not V beta, gene usage. Two of three predominant isletitis clonotypes of patient 2 were V alpha 22+ (19 of 28 cDNAs) and the other (5 of 28 cDNAs) was also V alpha 14+.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The Governance Symposium--Part II. A new context for trustees.

Today you are a hospital trustee. If health care reform doesn't scare you away, tomorrow you could be governing a system, a network, a physician/hospital organization, or a community hospital that belongs to one of these other entities. managed care will change your priorities, your responsibilities, and the expectations others have of you as well as the health care delivery system. To learn more about the trustee's role in a reformed health care system, the American Hospital Association and Trustee recently convened a governance symposium (see the list of participants on the opposite page). The first part of the discussion from that symposium was presented in the August issue (see "Quantum leap," page 6). The second part focuses on the issues of board accountability and compensation and realigning incentives for the future.

Governing Board↗
PubMed1994

Assessment of general practitioners' management of hyperlipidaemia. A study using personal visits and a scenario-based questionnaire.

In summary our study has looked at the current management practices of hyperlipidaemia by general practitioners in an innovative way. Our results suggest that most GPs are managing this condition appropriately. Where their management differs from current guidelines is mainly in introducing medication early. We obtained significantly lower participation rates in the metropolitan as compared with the regional and rural areas, but we found no significant differences in the overall assessment of appropriate management between the different geographical regions of Victoria.

Data Collection↗