A Short-Term Screening Protocol, Using Fibrillin-1 as a Reporter Molecule, for Photoaging Repair Agents

Photoaged skin is characterized by coarse and fine wrinkles. The mechanisms of wrinkle formation are undetermined, but appear to be due to changes within the matrix of the dermis and at the dermal-epidermal junction. Previous studies have identified marked reductions in procollagens I and III, collagen VII, and the fibrillin-rich microfibrillar apparatus in this area. Topically applied all-trans retinoic acid can repair photoaged dermal matrix, but this takes at least 6 mo of treatment. In this study, we have examined the abundance and distribution of fibrillin-1 prior to, and following, 192 wk of all-trans retinoic acid treatment. We have further developed a short-term protocol to determine the utility of potential repair agents, using fibrillin-1 as the marker for outcome. Individuals with clinically assessed severe photoaging were recruited to the study (n = 8). 0.025% all-trans retinoic acid, 5% sodium lauryl sulfate (irritant control), or vehicle were applied under occlusion to photoaged extensor forearm. A fourth control area was also occluded. After 96 h, punch biopsies were taken under local anesthesia and processed for either transmission electron microscopy or snap frozen. Frozen sections were prepared for immunohistochemistry and in situ hybridization immunohistochemistry. Electron microscopy revealed aberrant elastic fibers in the papillary dermis of photoaged forearm skin, with sparse microfibrillar apparatus and interstitial collagen. After application of 0.025% all-trans retinoic acid, there was increased deposition of both these dermal matrix components, with the aberrant elastic fibers no longer apparent. Significant increases (p < 0.05) were observed at the protein and mRNA levels for fibrillin-1 following all-trans retinoic acid and sodium lauryl sulfate treatments, with all-trans retinoic acid having a significantly greater effect than irritant control (p < 0.001); however, neither application had significant effect on the abundance of collagen VII or its mRNA. Investigation of collagen I synthesis revealed no difference following treatments. To ascertain the clinical relevance of using fibrillin-1 as a marker for photoaging, facial skin was biopsied at baseline and after long-term (192 wk) topical all-trans retinoic acid treatment (n = 5). Biopsies were wax-embedded and sections prepared for immunohistochemistry for fibrillin-1. Significant increases in the abundance of the microfibrillar apparatus was observed proximal to the dermal- epidermal junction (p < 0.001) following long-term all-trans retinoic acid application. This study indicates that all-trans retinoic acid can significantly affect fibrillin-1 content in photoaged skin. Furthermore, fibrillin-1 can be used as a "reporter" molecule in short-term protocols for testing the utility of topical agents in the repair of photoaged skin.

Performance evaluation of a Marshland Upwelling System for the removal of fecal coliform bacteria from domestic wastewater

The Marshland Upwelling System (MUS), a potential alternative wastewater treatment strategy for coastal dwellings, was examined to assess its ability to remove fecal coliforms (FC) from domestic wastewater as a step towards total treatment. Wastewater was intermittently injected down a 4.6-m injection well into the surrounding salt marsh. Optimal performance was achieved at an injection flowrate of 1.9 L/min and injection frequency of 30 minutes every 3 hours. Average influent concentrations of 930,000+/-650,000 colonies/100 mL, were reduced to effluent counts of 4.6 colonies/100 mL. Coliform removal followed exponential decay versus vector distance traveled with predicted surface concentrations less than or equal to 0.1 colony/100 mL. Hydraulic performance was acceptable with no significant reductions in permeability observed. Increasing flows to 3.8 L/min produced localized hydraulic dysfunction as indicated by sudden increases in effluent bacterial counts and injection pressures. Although fecal coliform removal typically decreased with increasing injection flowrates and isolated instances of abnormally high effluent counts were observed the MUS never experienced a catastrophic failure during the 13-month evaluation period.

Activation of oral keratinocytes by mercuric chloride: relevance to dental amalgam-induced oral lichenoid reactions

BACKGROUND

Despite the benefits of mercury-containing amalgam dental fillings there are growing concerns regarding the potential adverse health effects arising from exposure to mercury released from fillings. In some individuals this process may result in a local lichenoid reaction of the oral mucosa.

OBJECTIVES

The aim of this study was to investigate the possibility that mercury salts released from amalgam fillings might act directly on oral keratinocytes to induce changes that could promote the development of such lesions.

METHODS

In vitro experiments were performed in which normal oral and cutaneous keratinocytes were cultured in the presence of mercuric chloride (HgCl2). ICAM-1 expression and the release of cytokines was determined by enzyme-linked immunosorbent assay techniques. T-cell binding to HgCl2-pretreated keratinocytes was assessed using a colorimetric method.

RESULTS

Subcytotoxic concentrations of HgCl2 induced a concentration-related increase in ICAM-1 expression and consequent T-cell binding on oral, but not cutaneous, keratinocytes. HgCl2 also stimulated the release of low levels of tumour necrosis factor-alpha and interleukin-8 (but not RANTES), and inhibited the release of interleukin-1alpha by oral keratinocytes.

CONCLUSIONS

This study provides evidence that oral keratinocytes may play an integral part in initiating the pathogenesis of amalgam-induced lichenoid reactions.

Do race and gender influence the use of invasive procedures?

OBJECTIVE

To assess the influence of race and gender influence on the use of invasive procedures in patients with acute myocardial infarction (AMI) in community hospitals.

DESIGN

Prospective, observational.

SETTING

Five mid-Michigan community hospitals.

PATIENTS

All patients (838) identified with AMI between January 1994 and April 1995 in 1 of these hospitals.

MEASUREMENTS AND MAIN RESULTS

After adjusting for age, hospital of admission, insurance type, severity of AMI, and comorbidity, using white men as the reference group, the rate of being offered cardiac catheterization (CC) was 0.88 (95% confidence interval [95% CI], 0.60 to 1.29) for white women; 0.79 (95% CI, 0.41 to 1.50) for black men; and 1.14 (95% CI, 0.53 to 2.45)for black women. Among patients who underwent CC, after also adjusting for coronary artery anatomy, the rate of being offered angioplasty, using white men as the reference group, was 1.22 (95% CI, 0.75 to 1.98) for white women; 0.61 (5% CI, 0.29 to 1.28, P =.192) for black men; and 0.40 (95% CI, 0.14 to 1.13) for black women The adjusted rate of being offered bypass surgery was 0.47 (95% CI, 0.24 to 0.89) for white women; 0.36 (95% CI, 0.12 to 1.06) for black men; and 0.37 (95% CI, 0.11 to 1.28)for black women.

CONCLUSIONS

Our study shows that white women are less likely than white men to be offered bypass surgery after AMI. Although black men and women with AMI are less likely than white men to be offered percutaneous transluminal coronary angioplasty or coronary artery bypass grafting in both unadjusted and adjusted analyses, these findings did not reach statistical significance. Our study is limited in power due to the small number of blacks in the sample.

Distribution and expression of type VI collagen in photoaged skin

BACKGROUND

Several of the characteristic clinical features of photoaged skin, including wrinkling, are thought to be dependent on changes in the dermal matrix brought about by chronic sun exposure. Such changes include reductions in collagens I, III and VII, an increase in elastotic material in the reticular dermis and a marked reduction in the microfibrillar glycoprotein fibrillin.

OBJECTIVES

To examine whether type VI collagen, a microfibrillar collagen necessary for cell-cell and cell-matrix communication, is affected by the photoageing process.

METHODS

Six healthy volunteers with moderate to severe photoageing were enrolled into the study. Immunohistochemistry and in situ hybridization histochemistry were used to examine the levels of type VI collagen in photoprotected and photoaged sites.

RESULTS

In photoprotected skin, type VI collagen was concentrated in the papillary dermis immediately below the dermal-epidermal junction, around blood vessels, hair follicles and glandular structures. The distribution of type VI collagen was unchanged in photoaged skin, although we observed an increase in the abundance of the alpha3 chain of collagen VI in the upper papillary dermis, at its junction with the dermal-epidermal junction (P < 0.05). No alterations were observed for any alpha chain at the mRNA level.

CONCLUSIONS

These studies suggest that chronic sun exposure (photoageing) has little or no effect on either the distribution, abundance or levels of expression of type VI collagen in human skin. Thus, type VI collagen, unlike other matrix components so far studied, appears to be relatively unaffected by the photoageing process.

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.

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.

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.

Context-dependent nestmate discrimination in the paper wasp, Polistes dominulus: a critical test of the optimal acceptance threshold model

e present evidence that nestmate discrimination in the eusocial paper wasp, Polistes dominulus, is context dependent. We compared aggression levels between nestmates and non-nestmates in dyads consisting of a pair of either nestmates or non-nestmates, and triads consisting of either three nestmates, three non-nestmates, or two nestmates and a non-nestmate. In 130 of the 237 total trials, a nest fragment (containing both brood and eggs) from the nest of some, all or none of the interactants was placed into the interaction arena. Polistes dominulus workers recognized and discriminated nestmates from non-nestmates, familiar from unfamiliar nest material and neighbours from non-neighbours. These findings suggest that nestmate and neighbour discrimination are context dependent: discrimination occurs when either the presence of a nestmate or a familiar nest fragment indicate the proximity of the colony. The context-dependent variation in aggression levels is best described by multiple, context-dependent shifts in an acceptance threshold. Thus this study provides the most extensive, critical support yet obtained for Reeve's (1989, American Naturalist, 133, 407-435) optimal acceptance threshold model. Copyright 1998 The Association for the Study of Animal Behaviour

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.

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.

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.

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.

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.

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.

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.

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.