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Biomedical subjects

R E Watson

Publications and source records attributed to R E Watson.

At least 19 recordsLinked to original sources
PubMed2000

The use of angiotensin-converting enzyme inhibitors in patients with acute myocardial infarction in community hospitals. Michigan State University Inter-Institutional Collaborative Heart (MICH) Study Group.

BACKGROUND: Previous studies documenting underutilization of angiotensin-converting enzyme inhibitors (ACEIs) in acute myocardial infarction (AMI) have been limited to Medicare populations. HYPOTHESIS: This study examines ACEI prescription rates and predictors in a community sample of hospitalized patients with AMI. METHODS: The charts of 1163 community patients with AMI, prospectively identified at admission between January 1, 1994, and April 30, 1995, were reviewed. RESULTS: Only 64 of 158 (40%) patients considered ideal candidates for ACEI prescription were discharged with a prescription for an ACEI. In a multivariate logistic regression model, prior ACEI utilization [adjusted odds ration (OR) = 3.26; 95% confidence interval (CI) = 2.05-5.20], presence of congestive heart failure (OR = 2.33; CI = 1.50-3.61) and black race (OR = 2.20; CI = 1.34-3.64) were identified as positive predictors of ACEI prescription. Conversely, lack of left ventricular ejection fraction (LVEF) measurement (OR = 0.46; CI = 0.28-0.75), LVEF > 40 ( OR = 0.27; CI = 0.18-0.40), and acute renal failure (OR = 0.08; CI = 0.01-0.44) were negative predictors. Women were also less likely to be discharged with an ACEI prescription (OR = 0.71; CI = 0.48-1.05). Furthermore, women were significantly less likely to have LVEF measured prior to discharge than were males (77 vs. 85%, p = 0.001). CONCLUSION: This study underscores the need for improvement in the utilization of ACEI in eligible patients with AMI. It also identifies opportunities for improvement in prescription rates, especially in women.

Adult↗
PubMed1999

Detection of bovine immunodeficiency virus DNA in the blood and semen of experimentally infected bulls.

Five 18- to 24-month-old bulls were inoculated with either a cell suspension containing bovine immunodeficiency virus (BIV-FL112; 3 bulls) or a BIV-free cell suspension (2 bulls). Blood and semen specimens were collected once a week for 14 weeks, and seroconversion was confirmed by indirect immunofluorescent antibody (IFA) testing. The presence of BIV in blood and semen was determined by virus isolation and/or polymerase chain reaction (PCR) assays. Antibodies to BIV were detected in the 3 experimentally infected bulls as early as day post inoculation (DPI) 17, and levels peaked at DPI 37-58. BIV was isolated from the peripheral blood mononuclear cells (MNCs) of the infected bulls at DPI 9 (2 bulls) and DPI 23 (1 bull), and could be isolated from one animal up to DPI 65. PCR analysis of MNC DNA, using BIV pol gene primers, detected virus in all three of the experimentally infected bulls from DPI 9 until the termination of the experiment at DPI 98. Efforts to isolate a significant number of non-spermatozoal cells (NSC) by gradient separation from the semen of the experimentally infected bulls were unsuccessful. Two methods for the extraction of total NSC DNA from up to 2 ml of non-extended semen were employed; however, no BIV pol fragment was amplified from these DNA preparations. Additionally, 30 bulls from artificial insemination (AI) centers were evaluated for BIV infection by PCR. No amplification products were obtained from MNC DNA from the AI submissions using primer sets for both the BIV pol and env genes.

Animals↗
PubMed1999

Fibrillin-rich microfibrils are reduced in photoaged skin. Distribution at the dermal-epidermal junction.

Chronic sun exposure results in photoaged skin with deep coarse wrinkles and loss of elasticity. We have examined the distribution and abundance of fibrillin-rich microfibrils, key structural components of the elastic fiber network, in photoaged and photoprotected skin. Punch biopsies taken from photoaged forearm and from photoprotected hip and upper inner arm of 16 subjects with a clinical range of photoaging were examined for fibrillin-1 and fibrillin-2 expression and microfibril distribution. In situ hybridization revealed decreased fibrillin-1 mRNA but unchanged fibrillin-2 mRNA levels in severely photoaged forearm biopsies relative to photoprotected dermal sites. An immunohistochemical approach demonstrated that microfibrils at the dermal-epidermal junction were significantly reduced in moderate to severely photoaged forearm skin. Confocal microscopy revealed that the papillary dermal microfibrillar network was truncated and depleted in photoaged skin. These studies highlight that the fibrillin-rich microfibrillar network associated with the upper dermis undergoes extensive remodeling following solar irradiation. These changes may contribute to the clinical features of photoaging, such as wrinkle formation and loss of elasticity.

Adult↗
PubMed1998

Fibrillin microfibrils are reduced in skin exhibiting striae distensae.

Striae distensae (striae: stretch marks) are a common disfiguring condition associated with continuous and progressive stretching of the skin--as occurs during pregnancy. The pathogenesis of striae is unknown but probably relates to changes in those structures that provide skin with its tensile strength and elasticity. Such structures are components of the extracellular matrix, including fibrillin, elastin and collagens. Using a variety of histological techniques, we assessed the distribution of these extracellular matrix components in skin affected by striae. Pregnant women were assessed for the presence of striae, and punch biopsies were obtained from lesional striae and adjacent normal skin. Biopsies were processed for electron microscopy, light microscopy and immunohistochemistry. For histological examination, 7 microns frozen sections were stained so as to identify the elastic fibre network and glycosaminoglycans. Biopsies were also examined with a panel of polyclonal antibodies against collagens I and III, and fibrillin and elastin. Ultrastructural analysis revealed alterations in the appearance of skin affected by striae compared with that of normal skin in that the dermal matrix of striae was looser and more floccular. Light microscopy revealed an increase in glycosaminoglycan content in striae. Furthermore, the number of vertical fibrillin fibres subjacent to the dermal-epidermal junction (DEJ) and elastin fibres in the papillary dermis was significantly reduced in striae compared with normal skin. The orientation of elastin and fibrillin fibres in the deep dermis showed realignment in that the fibres ran parallel to the DEJ. However, no significant alterations were observed in any other extracellular matrix components. This study identifies a reorganization and diminution of the elastic fibre network of skin affected by striae. Continuous strain on the dermal extracellular matrix, as occurs during pregnancy, may remodel the elastic fibre network in susceptible individuals and manifest clinically as striae distensae.

Actin Cytoskeleton↗
PubMed1998

All-trans retinoic acid compromises desmosome expression in human epidermis.

An undesirable side-effect of retinoid treatment is skin fragility. As desmosomes are important in maintaining the cohesion of epidermal keratinocytes, we investigated whether all-trans-retinoic acid (RA) compromises desmosome expression in human epidermis, thereby predisposing skin to fragility. Solutions containing 0.025% RA, 5% sodium dodecyl sulphate (SDS) as an irritant control, or vehicle alone were applied to three sites on the buttocks of normal volunteers (n = 9). Treated sites were occluded for 4 days, and biopsies taken under local anaesthesia. Cryostat sections were stained with a panel of antibodies to desmosomal proteins and visualized by immunofluorescence microscopy. Stained sections were randomized and assessed for intensity of staining. The epidermal thickness of each treated site was quantified by image analysis. Western blots of epidermal desmocollins were quantified by densitometry. RA and SDS treatments significantly, but equivalently, increased epidermal thickness compared with vehicle. Immunohistochemically, both RA and SDS were shown to reduce epidermal staining for desmoplakin, desmoglein 1, plakophilin 1 and desmocollin 3 equally compared with vehicle-treated skin (P < 0.001). RA produced a greater reduction in desmocollin 1 staining compared with SDS (P < 0.001). Similar reductions in desmocollins were found by Western blot analysis. Reduced desmocollin expression may indicate compromised desmosomal adhesion, leading to the skin fragility that results from retinoid treatment.

Adult↗
PubMed1997

The medial capsule of the human temporomandibular joint.

PURPOSE: Attachments of the medial capsule of the temporomandibular joint (TMJ) to structures other than the medial fossa wall are thought to exist and to have functional significance. This study evaluated these relationships. MATERIALS AND METHODS: The anatomic relationships between the medial capsule and other medial structures, the sphenomandibular ligament, discomalleolar ligament, and auriculotemporal nerve, were examined in 14 cadaver heads. RESULTS: The results showed that the sphenomandibular ligament attaches separately from the medial capsule of the TMJ and therefore has no functional significance to the biomechanics of the joint. The discomalleolar ligament was found to be a continuation of the retrodiscal tissues and minimally associated with the medial capsule. The auriculotemporal nerve was not found to be in a relationship with the medial aspect of the condyle to the extent that mechanical irritation is possible during TMJ movement or disc displacement.

Aged↗
PubMed1997

Clinical features of photodamaged human skin are associated with a reduction in collagen VII.

Chronically sun-exposed or photodamaged human skin is characterized by a number of clinical features, including wrinkles. However, little is known about the molecular mechanisms that underlie these features. We investigated the hypothesis that the mechanism of wrinkle formation may involve loss of anchoring fibrils, composed mainly of collagen VII, which are important in maintaining dermal-epidermal junction integrity. Ten volunteers with moderate to severe photodamage of dorsal forearm skin were recruited to the study. Using immunohistochemistry, transmission electron microscopy and in situ hybridization, we compared collagen VII protein and mRNA content of photodamaged forearm skin with that of sun-protected hip and upper inner arm skin from the same subjects. Numbers of anchoring fibrils per linear microns of basement membrane (mean +/- SEM) were significantly lower in photodamaged skin (1.79 +/- 0.10) as compared with sun-protected hip (2.28 +/- 0.11) and upper inner arm skin (2.21 +/- 0.10) (P < 0.01), and similarly keratinocyte expression of collagen VII mRNA, quantitated as number of positively stained keratinocytes per high power field, was significantly reduced in photodamaged skin (6.3 +/- 2.5) as compared with sun-protected hip (20.0 +/- 5.6) and upper inner arm skin (17.7 +/- 4.9) (P < 0.001). Semiquantitative assessment of immunohistochemical staining for collagen VII showed a non-significant reduction in photodamaged skin as compared with sun-protected skin. We propose that reduced content of collagen VII in photodamaged skin contributes to wrinkle formation by weakening the bond between the dermis and epidermis.

Aged↗
PubMed1997

Myers-Briggs Type Indicator and dental school performance.

The Myers-Briggs Type Indicator (MBTI) was administered to 256 dental students, representing four classes, at the University of Florida College of Dentistry. The results of this psychological instrument were then correlated with overall dental school performance based on results from the National Dental Board Examinations Part I and II (NB-I, NB-II), yearly class rank, and specific academic difficulties as measured by the Student Performance Evaluation Committee. Introverted students were found to display a significantly increased performance on NB-I (p = .038) and NB-II (p = .044). They were also found, however, to demonstrate a progressively lower class rank over the four-year period than extroverted students and were more likely to experience major academic difficulties as well. Judging and sensing individuals were found to earn a higher class rank over the four-year period than perceiving and intuitive students, respectively. Perceiving students were found to exhibit major difficulties or were placed on probation more often than judging individuals. These results may prove useful in counseling students to recognize potential problems before they commence their dental education or to anticipate and address specific weaknesses during the course of their education.

Achievement↗
PubMed1996

The hypothalamic ventromedial nucleus sends a met-enkephalin projection to the preoptic area's periventricular zone in the female rat.

The female but not the male rat possesses a dense network of methionine enkephalin (m-Enk) fibers in the periventricular zone of the preoptic area (pePOA). The potential source of these fibers was determined by injection of the tracer fluorogold, FAu, into the preoptic area of adult female rats. Twenty-four hours before they were killed, the rats were administered colchicine (intraventricularly) to enable immunocytochemical visualization of m-Enk cells. Upon examination of the brains with fluorescence microscopy, double-labeled cells showing fluorogold and immunofluorescence for m-Enk were consistently observed in the preoptic area, the ventrolateral division of the ventromedial nucleus of the hypothalamus (VMHvl) and nearby medial tuberal area (MTA), the arcuate nucleus, periventricular area of the hypothalamus, perifornical area, and dorsomedial nucleus of the hypothalamus. A series of lesion and knife cut experiments using glass, Halasz, and wire knives determined that the pePOA m-Enk fibers arose from the hypothalamus, near or within the VMH. Ibotenic acid lesions further determined that the source of the m-Enk projection was the VMHvl with a possible additional contribution from the MTA.

Animals↗
PubMed1996

Muscle attachment to the lateral aspect of the articular disk of the human temporomandibular joint.

OBJECTIVE: To investigate the anatomic attachments to the lateral aspect of the anterior band of the human temporomandibular joint articular disk. MATERIAL AND METHODS: Sixteen human cadaver half-heads were dissected and examined macroscopically. RESULTS: No direct attachment was observed between the deep masseter muscle and the temporomandibular joint articular disk. In one specimen, a small band of the anterior temporalis muscle was directly attached to the lateral aspect of the temporomandibular joint disk; whereas, on the same specimen, the attachment of the superior belly of the lateral pterygoid muscle was a comparatively large band. In another specimen, the lateral pterygoid muscle passed in an anterolateral direction. CONCLUSIONS: The masseter muscle has no functional significance in the biomechanics of temporomandibular joint disk displacement. The anterior temporalis muscle may have functional significance when it is accompanied by an anterolaterally divergent lateral pterygoid muscle.

Aged↗
PubMed1995

Estrogen-receptive neurons in the anteroventral periventricular nucleus are synaptic targets of the suprachiasmatic nucleus and peri-suprachiasmatic region.

The anteroventral periventricular nucleus (AVPv) in the rat preoptic area is a key site underlying control of the steroid dependent preovulatory gonadotropin surge. Estrogen and progesterone receptor-containing neurons in the preoptic/hypothalamic continuum, particularly those in the AVPv, are believed to transduce steroidal signals and, in turn convey this information to the LHRH system, which lacks steroid receptors. In addition to the influence of the gonadal steroids, the precise timing of the preovulatory gonadotropin surge is believed to be regulated by the hypothalamic suprachiasmatic nucleus (SCN). The SCN and peri-SCN neurons send efferent projections rostrally to the anterior preoptic area suggesting that circadian signals are communicated synaptically to steroid-responsive neurons in the AVPv. To test this hypothesis, ultrastructural double label immunocytochemistry was conducted to determine whether SCN efferents contact estrogen receptor-immunoreactive neurons in the AVPv. Brain sections with SCN injections of phaseolus vulgaris leucoagglutinin (PHA-L) were immunostained for estrogen receptors and PHA-L. Light and electron microscopic data show that the anterior preoptic area received robust PHA-L-immunoreactive efferents from SCN neurons and immediately adjacent subparaventricular zone. In particular, the AVPv contained abundant labeled fibers and terminal boutons. Ultrastructurally, SCN- and subparaventricular zone-derived terminals synaptically contacted the perikaryon of many estrogen receptor-immunoreactive neurons in the AVPv. The perikarya of unlabeled neurons were also contacted, but the majority of the labeled contacts were observed upon neuronal processes. These results demonstrate that estrogen responsive AVPv neurons are regulated by SCN efferents. Furthermore, the present data provide strong support to the idea of collective control of pituitary gonadotropin release by steroid sensitive and circadian signal neural pathways.

Animals↗
PubMed1995

Distribution of natriuretic peptide precursor mRNAs in the rat brain.

Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP) represent members of a recently discovered neuropeptide family involved in central regulation of endocrine and autonomic functions. The present study employed an in situ hybridization approach to provide the first detailed comparative mapping of ANP, BNP, and CNP mRNAs in brain. Results indicate that ANP mRNA is highly expressed in anterior olfactory nuclei, limbic cortices, dorsal endopiriform nucleus, hippocampal subfield CA1, cortical amygdaloid nuclei, medial habenula, anteroventral periventricular and arcuate nuclei, periventricular stratum, zona incerta, mammillary nuclei, inferior olive, nucleus ambiguus, and pontine paragigantocellular nuclei. CNP mRNA is expressed at highest levels in olfactory nuclei, limbic cortices, dorsal endopiriform nucleus, hippocampal subfields CA1-3, anteroventral periventricular and arcuate nuclei, and numerous brainstem regions (including the pontine, lateral reticular, solitary tract, prepositus hypoglossal, and spinal trigeminal nuclei). Positive labeling for BNP mRNA was not observed in brain. The presence of both ANP and CNP mRNA in the same regions of distinct nuclei (e.g., the anteroventral periventricular and arcuate nuclei) suggests the potential for coexpression. Overall, the present data are consistent with a prominent role for both ANP and CNP in neuroendocrine regulation and central cardiovascular integration. The extensive localization of ANP and/or CNP mRNA in olfactory nuclei, limbic cortex, hippocampus, amygdala and diencephalic limbic relays further indicate a putative role for ANP and CNP as neuromodulators of olfactory/limbic information processing.

Animals↗
PubMed1995

The C-type natriuretic peptide receptor is the predominant natriuretic peptide receptor mRNA expressed in rat hypothalamus.

The natriuretic peptide receptors (NPR) are membrane-bound guanylate cyclases with extracellular binding domains specific for particular members of the natriuretic peptide family. NPR-A binds atrial natriuretic peptide (ANP) with high affinity, whereas the NPR-B appears to be specific for C-type natriuretic peptide (CNP). Previous data indicating extensive overlap between localization of ANP and CNP in hypothalamic neuroendocrine circuits suggest the importance of determining whether specificity of natriuretic peptide action may be conferred via receptor type present on target cells. To address this issue, we used in situ hybridization histochemistry to localize NPR-A and NPR-B mRNA in the hypothalamus. NPR-A mRNA was not found in substantial abundance in any hypothalamic nucleus; however, detectable NPR-A signal was observed in other brain regions, including the subfornical organ and medial habenula. In contrast, NPR-B mRNA was expressed throughout the hypothalamus, including neurons of the magnocellular and parvocellular paraventricular, the arcuate, and the supraoptic nuclei. Expression was also seen in other nuclei essential to neuroendocrine control, including the median preoptic, anteroventral periventricular, tuberomammilary, ventromedial and suprachiasmatic nuclei. NPR-B mRNA was also observed in the neural lobe of the pituitary gland, suggesting expression by pituicytes. The results suggest that NPR-B is the primary natriuretic peptide receptor in hypothalamus, and by inference indicate that CNP is the primary active natriuretic peptide in neuroendocrine regulation.

Animals↗
PubMed1994

Estrous cycle-associated axosomatic synaptic plasticity upon estrogen receptive neurons in the rat preoptic area.

This study examined the hypothesis that synaptic relationships change on a daily basis in the anterior preoptic area of the intact, cycling female rat. Specifically, the anteroventral periventricular nucleus (AVPv) was chosen for analysis due to its abundant estrogen- and progesterone-receptive neurons and its critical role in the control of gonadotropin secretion. Ultrastructural analysis revealed that in the 24 h between proestrus and estrus, there was a 39% increase in axosomatic synapses upon AVPv neurons. In the subsequent 24 h to metestrus, the number of synapses decreased by 22%. Additional data showed that ovariectomy resulted in more axosomatic synapses in the AVPv relative to proestrus (46%) and metestrus (35%). Another component of the study investigated synaptic relationships on estrogen receptor-immunoreactive (ER-ir) and non-ER-ir neurons across the estrous cycle. ER-ir neurons received significantly more synaptic input at proestrus and estrus than did non-ER-ir neurons. At metestrus and following ovariectomy, no significant differences were present. The present study indicates that estrous cycle-associated synaptic plasticity occurs in the AVPv and lends further support to the critical role of this nucleus in regulation of gonadotropin secretion. Moreover, it provides the first evidence that ER- and non-ER-ir neurons are differentially innervated.

Animals↗
PubMed1994

Case report: transverse colon volvulus in a patient with Clostridium difficile pseudomembranous colitis.

Sixty-eight cases of transverse colon volvulus have been reported in the literature. The authors report the first case of transverse colon volvulus in association with Clostridium difficile pseudomembranous colitis, with a review of the available literature. It is possible that the acute inflammation of the colonic mucosa, which occurred from the pseudomembranous colitis in this patient, contributed to the development of volvulus. Further studies are needed to explore the role of mucosal inflammation in the occurrence of volvulus.

Clostridioides difficile↗