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Biomedical subjects

R Bennett

Publications and source records attributed to R Bennett.

At least 37 records · Page 2Linked to original sources
PubMed1996

Dental health of aboriginal pre-school children in Brisbane, Australia.

This investigation studied the dental health status of a group of 184 Australian Aboriginal children with a mean age of 4.4 +/- 0.8 years, who were attending pre-schools in metropolitan Brisbane, a non-fluoridated state capital city. The DDE (Developmental Defects of Enamel) Index was used to chart enamel hypoplasia and enamel opacities. WHO criteria was used to diagnose dental caries. The results showed that 98% of children had at least one tooth showing developmental enamel defects. Each child had a mean of 3.8 +/- 1.7 teeth affected by enamel hypoplasia and another 1.1 +/- 0.8 teeth affected by enamel opacity. Seventy-eight percent of the children had dental caries. The mean number of decayed, missing, filled teeth (dmft) per child was 3.8 +/- 3.7. The decayed component constituted 3.5 (95%) of the mean dmft, indicating a high unmet restorative need in this group. The mean dmfs (decayed, missing, filled, surfaces) was 5.9 +/- 7.3. Maxillary anterior labial decay of at least one tooth affected 43 (23%) of the children. In this sub-group, the dmft and dmfs was 9.1 +/- 2.8 and 15.4 +/- 7.7 respectively. Oral debris was found in 98% of the children. It is hypothesized that the high levels of underlying developmental enamel defects, compounded by low fluoride exposure, poor oral hygiene and a diet high in refined sugars pose an important caries risk factor in this group of children.

Child, Preschool↗
PubMed1996

Maternal risks for very low birth weight infant mortality.

OBJECTIVE: To determine whether known maternal risk factors for low birth weight directly contribute to infant mortality among very low birth weight infants. DESIGN: Retrospective population-based, case-control study. SETTING: Four hospitals in the Oakland, California, area: one community, two private, one health maintenance organization. PARTICIPANTS: All live-born singleton very low birth weight ( < 1500 g) infants born to Oakland residents over a 3-year period. Cases were infants who died before their first birthday, identified by computerized linkage of birth and death certificates. For each case, a surviving control was selected to match for birth weight, sex, and race. Forty matched pairs were identified in total. OUTCOME MEASURES: Prevalence of maternal risk factors among cases versus controls. RESULTS: After controlling for other factors known to influence either birth weight or infant mortality, maternal cocaine use (odds ratio [OR] = 5.43), prior infant death (OR = 27.14), and planned pregnancy (OR = 6.33) were significantly associated with the survival of very low birth weight infants. CONCLUSIONS: Some maternal risk factors for low birth weight confer a survival advantage to very low birth weight infants. Our data reveal that maternal cocaine use is independently associated with survival among this subset of infants. Prior research supports the observed relationship as well as the scientific plausibility of a cocaine-mediated survival advantage among premature infants. Our study also showed both planned pregnancy and prior infant death to be independently associated with infant survival among this subset of infants, suggesting that maternal behaviors may play a role in determining birth weight-specific mortality. These data should be systematically evaluated to better define their relationship to infant mortality.

Adolescent↗
PubMed1996

The association of systemic lupus erythematosus and Lambert-Eaton myasthenic syndrome.

The association of systemic lupus erythematosus (SLE) and myasthenia gravis is well known. However, the association between SLE and Lambert-Eaton myasthenic syndrome (LEMS) is described in only 2 cases. We describe the case of a 31-year-old woman with SLE who presented with severe, predominantly proximal muscle weakness of subacute onset. The diagnosis of LEMS was based on her distinctive clinical and electrophysiological findings. She was treated successfully with plasmapheresis and oral prednisone. She remains in remission 6 months after this episode.

Action Potentials↗
PubMed1995

The desmocollins of human foreskin epidermis: identification and chromosomal assignment of a third gene and expression patterns of the three isoforms.

A third human desmocollin, designated DSC3, was identified in foreskin epidermis by reverse transcriptase-polymerase chain reaction (PCR) using degenerate desmocollin primers. cDNA clones covering the entire coding sequence of the longer DSC3 splice variant were isolated and sequenced. Sequence comparisons indicated that this new desmocollin showed greater homology (67% amino acid identity) with the original human desmocollin (now designated DSC2) than with DSC1 (52% amino acid identity) although it had a unique potential cell adhesion recognition site (YAS). DSC3 was assigned to chromosome 18 by PCR analysis of rodent-human somatic cell hybrids, where it appears to be closely linked to all the other desmosomal cadherin genes. The expression of the three human desmocollins was examined in foreskin epidermis by in situ hybridization with 3'-untranslated riboprobes and by immunofluorescence with isoform-specific anti-peptide antibodies. DSC1 was present in the upper spinous/granular layers but not in the basal/lower spinous layers of the tissue. DSC2 and DSC3 were present in most of the living layers of the epidermis. DSC1 was not detected in any of the nonkeratinizing human epithelia examined (buccal mucosa, cervix, esophagus), indicating that it is specific for the keratinizing epithelium of the epidermis. However, all these internal epithelia expressed DSC2 and DSC3, and both were present in most of the living layers of the tissues including the basal layers.

Amino Acid Sequence↗
PubMed1995

Feeding behavior in the nocturnal moth Manduca sexta is mediated mainly by blue receptors, but where are they located in the retina?

The spectral sensitivity of nectar feeding by adults of the tobacco hawkmoth Manduca sexta was measured in free-choice experiments. The action spectrum displayed a narrow peak at 450 nm and a low secondary maximum at 560 nm. Thus, the feeding response is mediated primarily by blue-sensitive receptors containing the Manduca sexta photopigment P450, while green-sensitive receptors containing P520 play a minor role. A minimum at 500 nm separating the two peaks suggests mutual inhibition between green and blue receptors or negative interaction more proximally in the visual system. The action spectrum drops off abruptly at 400 nm, in accordance with an earlier finding that ultraviolet wavelengths, discerned by receptors containing P357, obstruct the feeding response. The spectral sensitivity of the Manduca sexta compound eye, determined by electroretinogram recordings, and earlier visual pigment measurements indicate that approximately 75 % of the receptors are green-sensitive, with the remainder divided between blue- and ultraviolet-sensitive cells. The distribution of receptor types in small areas of the retina was measured by their ultrastructural response to light. Green and ultraviolet receptors were found, but not the blue receptors that dominate the feeding response. Possibly they are concentrated in a particular region of the retina that has not yet been found.

Journal Article↗
PubMed1994

Fertility considerations in nerve-sparing retroperitoneal lymph-node dissection.

Nerve-sparing retroperitoneal lymph-node dissection (RPLND) maintains the patient's ability to ejaculate postoperatively. However, since testicular cancer patients sometimes have diminished spermatogenesis, questions have been raised as to the advisability of nerve preservation relative to ultimate fertility. Fertility status was assessed in clinical stage A patients by two methods. These included standard semen analysis and a post-RPLND survey. The results show that approximately 75% of non-seminomatous testicular cancer patients who present in clinical stage A have fertility potential as based on semen analysis. Additionally, of those patients responding to the post-RPLND survey who had attempted pregnancy following RPLND, 76% reported attainment of pregnancy. Nerve-sparing RPLND maintains fertility potential in clinical stage I patients; furthermore, this fertility potential appears to be worth preserving as many patients will be capable of impregnating their partners.

Ejaculation↗
PubMed1994

The fertility of patients with clinical stage I testis cancer managed by nerve sparing retroperitoneal lymph node dissection.

Nerve sparing retroperitoneal lymph node dissection reliably preserves emission and ejaculation in patients with clinical stage I nonseminoma. The fertility of 51 patients who underwent nerve sparing retroperitoneal lymph node dissection was assessed by 3 different methods: standard semen analysis, analysis of chromatin content by deoxyribonucleic acid histogram and assessment of ultimate fertility status by a questionnaire. Approximately 75% of these patients have semen analyses generally considered to be in the normal range. Virtually all patients who underwent deoxyribonucleic acid histogram analysis had histograms similar to controls. A retrospective analysis of fertility was performed in 201 patients who had previously undergone nerve sparing retroperitoneal lymph node dissection. Of these patients who attempted pregnancy after nerve sparing retroperitoneal lymph node dissection 76% have been successful. Approximately 75% of patients who present with clinical stage I nonseminoma are potentially fertile. Nerve sparing retroperitoneal lymph node dissection is capable of preserving this potential in allowing these patients to father children.

Female↗
PubMed1994

A longterm endoscopic evaluation of patients with arthritis treated with nabumetone vs naproxen.

OBJECTIVE: To compare the gastrointestinal safety, ulcerogenic potential, and clinical efficacy over 5 years of nabumetone and naproxen therapy, in patients with rheumatoid arthritis (RA) or osteoarthritis (OA). METHODS: Fifty-two patients entered a randomized, double blind study. Patients were randomized to 3 months treatment with either nabumetone, 1000 mg nightly, or naproxen, 250 mg twice daily, followed by an endoscopist-blind 5-year followup study. After the double blind phase, 15 patients in the nabumetone group and 12 in the naproxen group continued in the longterm endoscopist-blind phase. Endoscopic evaluations for gastroduodenal damage and global assessments of arthritis activity and degree of pain for efficacy were measured. RESULTS: Over the 5-year period, endoscopically visible gastroduodenal ulceration was found in 8 of the naproxen treated patients compared with one of the nabumetone treated patients (p = 0.02). There was a significant difference in the time to develop an ulcer, with a greater risk of developing an ulcer sooner while taking naproxen (p < 0.01). Patients in both groups reported significant improvements in arthritis symptoms (p < 0.01). CONCLUSION: Nabumetone appears to have a significantly lower ulcerogenic potential than naproxen over a 5-year period, and there is a trend toward better tolerability as measured by withdrawals for adverse experiences.

Aged↗
PubMed1994

Deletions spanning the neurofibromatosis 1 gene: identification and phenotype of five patients.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder characterized by marked variation in clinical severity. To investigate the contribution to variability by genes either contiguous to or contained within the NF1 gene, we screened six NF1 patients with mild facial dysmorphology, mental retardation, and/or learning disabilities, for DNA rearrangement of the NF1 region. Five of the six patients had NF1 gene deletions on the basis of quantitative densitometry, locus hemizygosity, and analysis of somatic cell hybrid lines. Analyses of hybrid lines carrying each of the patient's chromosomes 17, with 15 regional DNA markers, demonstrated that each of the five patients carried a deletion > 700 kb in size. Minimally, each of the deletions involved the entire 350-kb NF1 gene; the three genes--EVI2A, EVI2B, and OMG--that are contained within an NF1 intron; and considerable flanking DNA. For four of the patients, the deletions mapped to the same interval; the deletion in the fifth patient was larger, extending farther in both directions. The remaining NF1 allele presumably produced functional neurofibromin; no gene rearrangements were detected, and RNA-PCR demonstrated that it was transcribed. These data provide compelling evidence that the NF1 disorder results from haploid insufficiency of neurofibromin. Of the three documented de novo deletion cases, two involved the paternal NF1 allele and one the maternal allele. The parental origin of the single remaining expressed NF1 allele had no dramatic effect on patient phenotype. The deletion patients exhibited a variable number of physical anomalies that were not correlated with the extent of their deletion. All five patients with deletions were remarkable for exhibiting a large number of neurofibromas for their age, suggesting that deletion of an unknown gene in the NF1 region may affect tumor initiation or development.

Adolescent↗
PubMed1993

A preliminary report: postoperative fertility assessment in nerve-sparing RPLND patients.

Nerve-sparing RPLND is a procedure suited to patients with clinical stage I nonseminoma. Additionally, nerve-sparing techniques are applicable to patients with higher stage disease. Although ejaculation is reliably preserved with nerve-sparing techniques, the question of these patients' fertility has remained. Fertility was assessed in these patients by two techniques: laboratory analysis of semen and a post-RPLND questionnaire. Semen analyses and DNA histograms suggested fertility in > 70%; in addition, 43 of 53 (81%) patients who have tried to father children post RPLND have been successful. Nerve-sparing RPLND appears to be able to preserve fertility potential in these patients.

DNA, Neoplasm↗
PubMed1993

Regional blood flow, oxidative metabolism, and glucose utilization in patients with recent myocardial infarction.

BACKGROUND: Metabolic imaging with positron emission tomography (PET) can detect tissue viability in clinical infarct regions. With appropriate tracer kinetic models and serial PET imaging, regional myocardial blood flow and rates of metabolism can now be quantified in patients with recent myocardial infarctions. METHODS AND RESULTS: Serial PET imaging with [13N]ammonia, [11C]acetate, and 18F-deoxyglucose was performed in 22 patients with recent infarctions to measure regional blood flow (in milliliters per gram per minute), glucose metabolism (in micromoles per gram per minute), and oxidative metabolism (in clearance rate per minute). Hypoperfused clinical infarct regions were classified as "PET mismatch" if 18F was increased relative to 13N activity or "PET match" if 13N and 18F activities were reduced concordantly. Blood flows differed significantly between normal, mismatch, and match segments (0.83 +/- 0.20, 0.57 +/- 0.20, and 0.32 +/- 0.12 mL.g-1.min-1, respectively). The relation between oxidative metabolism and blood flow was piecewise linear and differed significantly between PET mismatch and PET match. Oxidative metabolism was less severely reduced than blood flow in mismatch regions but but reduced in proportion to blood flow in match regions. There was considerable overlap of blood flows between both types of PET segments. CONCLUSIONS: Quantification of regional blood flow and substrate metabolism in postinfarction patients revealed alterations in the relation between substrate delivery and consumption demonstrated previously only in invasive animal experiments. The preserved oxidative metabolism in myocardium with PET mismatches may be ascribed to a regional increase in oxygen extraction. Such increase together with preserved glucose utilization may be the prerequisite for survival of ischemically injured myocardium.

Coronary Angiography↗
PubMed1992

Lack of care giver hand contamination with endemic bacterial pathogens in a nursing home.

Prevalences of Clostridium difficile and multiply resistant Staphylococcus aureus (MRSA) were determined in nursing staff and residents of a 233-bed long-term care facility. Twenty of 38 (52.6%) patients in the long-term care ward and three of 69 (4.3%) in the skilled-nursing ward were colonized with MRSA; 16 of 48 (33%) patients in the long-term care ward and seven of 52 (13%) in the nursing home ward were colonized with C. difficile. None of the 79 staff members whose hands were cultured had chronic C. difficile hand carriage and MRSA was present on only three of 79 (3.9%). Over a 6-month period, 128,000 pairs of gloves were worn. Since C. difficile and MRSA are rarely present on washed hands of care providers, appropriate handwashing and gloving should make a significant contribution to reducing the spread of these agents in long-term care facilities.

Adult↗
PubMed1992

Expression of Ulex europaeus agglutinin I lectin-binding sites in squamous cell carcinomas and their absence in basal cell carcinomas. Indicator of tumor type and differentiation.

Lectins bind tightly to carbohydrate moieties on cell surfaces. Alterations in lectin binding have been reported to accompany epidermal cell differentiation, marking alterations in membrane sugars during this process. The presence of UEA I (Ulex europaeus agglutinin I) L-fucose-specific lectin-binding sites has been used as a marker for terminally differentiated (committed) keratinocytes. In this article, we report the presence of UEA-I-binding sites on squamous keratinocytes of well-differentiated squamous cell carcinomas, with patchy loss of UEA I positivity on poorly differentiated cells of squamous cell carcinomas, suggesting a possible use for this technique in the rapid assessment of less differentiated areas within the squamous cell tumor. The absence of UEA-I-binding sites on basal cell carcinomas may be related to an inability of cells comprising this tumor to convert the L-D-pyranosyl moiety on basal cells to the L-fucose moiety, resulting in an inability of basal cell carcinoma cell to undergo terminal differentiation into a committed keratinocyte.

Basal Cell Carcinoma↗