Beta-lactoglobulin suppresses melanogenesis in cultured human melanocytes

Eight cases of cervical necrotizing fasciitis are presented. Three were odontogenic, two were pharyngeal in origin and three were primary or idiopathic. Soft tissue gas was recognized in four patients. The bacteriology showed streptococci on the top of the list (50%), while for the idiopathic cases, it was monomicrobial and caused by staphylococci. Third generation cephalosporin and metronidazole represent good initial empirical antibacterial coverage. Histopathologically, all cases showed extensive necrosis of the debrided fascia and vascular thrombosis of the dermal vessels. The mortality rate was 3/8 (37.5%). Early diagnosis of cervical necrotizing fasciitis and initiation of definitive therapy in an intensive care environment is essential to minimize mortality. It is also important to recognize that this devastating infection may occur spontaneously, and it should be suspected in patients with unexplained soft tissue pain and tenderness.     

Stereological image analysis of cultured human melanocytes observed by transmission electron microscopy

The aims of the study were to write an image analysis (IA) program allowing the stereological quantification of human epidermal melanocyte melanization at the ultrastructural level and to specify the suitable preparative methods, in keeping with IA limits and stereological principles. Micrographs of cultured human melanocytes obtained in transmission electron microscopy were digitized with a scanner. The key step of the designed IA program is a thresholding based on the gray levels. Hence, gray level histograms (pixel frequency as a function of gray level) of melanocyte images exhibit a peak specific to melanin. The gray level thresholding used consists in isolating the melanin pixels that form profiles on a binary image and in storing the numerical data produced for a given melanocyte profile. These primary data are used to calculate numerous parameters via stereology with melanocyte cytoplasm and melanized melanosome as main reference spaces. The most important stereological parameters obtained are v(mi,cy) (melanin volume per average cell), v(mi,m) (melanin volume per average melanized melanosome), and nm (number of melanized melanosomes per average cell), and their validity is discussed. Melanocytes embedded in situ were abandoned for stereological reasons but pelleted melanocytes were found suitable. Using this computerized tool and stereology, we are able to perform quantitative studies producing varied data even from small cell samples. To our knowledge, this is the first stereological approach for quantifying intracellular melanization. A quantitative comparison of spectrophotometrical results (melanin assay) with stereological results obtained in ultraviolet B-irradiated Caucasian epidermal melanocytes will be performed in order to appraise this method.     

Detection of antibodies to melanocytes in vitiligo by western immunoblotting

To more fully define the nature of the antibody response to melanocytes which is associated with vitiligo, a Western immunoblot assay was used to test the sera of 28 patients with vitiligo (21 with active non-segmental, and 7 with stable segmental diseases) and 26 normal individuals for antibodies to antigens in detergent extracts of melanocyte membrane fractions. Antibodies to melanocytes were found in 26 (93%) of the patients with vitiligo, and in 16 (62%) of the control individuals. Patients with vitiligo and control individuals both had antibodies to an 80 approximately 83 kD antigen. The patient with vitiligo, in addition, had antibody responses to antigens with MWs of 45, 65, and 110 kD. Antibodies to these antigens were present in 46, 25, and 31% of vitiligo patients, but in only 19%. 0%, amd 0%, respectively, of the normal individuals. The heterogeneity of the antibody responses to melanocytes in vitiligo was further confirmed by the presence of antibodies to at least 3 distinct antigens in one-third of vitiligo patients but in none of the normal individuals. There was no difference in antibody response between patients with generalized and segmental vitiligo, suggesting that the pathogenesis of diseases was similar in both cases.     

(Pheo)melanin photosensitizes UVA-induced DNA damage in cultured human melanocytes

The question of whether melanins are photoprotecting and/or photosensitizing in human skin cells continues to be debated. To evaluate the role of melanin upon UVA irradiation, DNA single-strand breaks (ssb) were measured in human melanocytes differing only in the amount of pigment produced by culturing at two different concentrations, basic (0.01 mM) or high (0.2 mM), of L-tyrosine, the main precursor of melanin. In parallel, pheo- and total melanin contents of the cells were determined. Identical experiments were performed with two melanocyte cultures derived from a skin type I and a skin type VI individual. For the first time the correlation between UVA-induced genotoxicity and pheo-/total melanin content has been investigated. We observed that cultured in basic medium, the skin type VI melanocytes contained 10 times more total melanin and about seven times more pheomelanin than the skin type I melanocytes. Elevation of tyrosine level in the culture medium resulted in an increase of both pheo- and total melanin levels in both melanocyte cultures; however, the melanin composition of skin type I melanocytes became more pheomelanogenic, whereas that of skin type VI melanocytes remained the same. The skin type VI melanocytes cultured in basic medium demonstrated a very high sensitivity (1.18 ssb per 10(10) Da per kJ per m2) toward UVA that is probably related to their high pheo- and total melanin content. Their UVA sensitivity, however, did not change after increasing their melanin content by culturing at high tyrosine concentration. In contrast, the skin type I melanocytes demonstrated a low sensitivity (0.04 ssb per 10(10) Da per kJ per m2) toward UVA when cultured in basic medium, but increasing their melanin content resulted in a 3-fold increase in their UVA sensitivity (0.13 ssb per 10(10) Da per kJ per m2). These results demonstrate that UVA-irradiated cultured human melanocytes are photosensitized by their own synthesized chromophores, most likely pheomelanin and/or melanin intermediates.     

No high affinity melatonin binding sites are detected in murine melanoma cells and in normal human melanocytes cultured in vitro

Samples of 1815 cerebrospinal fluid (CSF) were studied in a meningitis outbreak during 1989 in S?o Paulo, Brazil. Neisseria meningitis 56% with 44% type B, Haemophilus influenzae 17%, from which 72% in children (days to 3-year-old) and Streptococcus pneumoniae 14% from which 60% in children (day to 1-year-old) of 443 (24%) of all strains. Cytochemistry study showed: purulent or turbidity aspects in 70 to 79% positive bacterioscopy or culture of CSF; white cells count > 500/mm3; glucose < 45 mg/dl; protein > 90 mg/dl in 90% of all patients. We concluded that: CSF prognostic factors: (aspect and cytochemistry) were correlated with bacterial meningitis. Bacterioscopy and positive cultures were correlated to NM, SP and HI isolation from these patients (Goodman Test).     

Effect of arbutin on melanogenic proteins in human melanocytes

OBJECTIVE: Peritonsillar sepsis (PTS) can be divided into abscess and cellulitis. It is the most common deep neck infection in the paediatric age group. In this article we discuss the clinical issues related to peritonsillar sepsis in children. METHOD: This study involves 185 cases of peritonsillar that were treated at the Montreal Children's Hospital in the last 10 years. The symptoms, signs, laboratory and radiological data as well as the medical and surgical therapies are included. RESULTS: Seventy-five cases were peritonsillar cellulitis (PTC) and the rest were abscesses. The age at presentation varied between 2.5 months and 18 years. The majority of the cases diagnosed as peritonsillar abscess (PTA) occurred from age 12 to 18 years. Trismus was the only complaint that was statistically associated with PTA. Uvular deviation combined with trismus was also important in differentiating PTA from PTC. Our data revealed a lower percentage of anaerobic bacteria and the majority of cultures grew Streptococcus pyogenes group A. CONCLUSIONS: Clinical picture is important in differentiating PTA from PTC. Recurrence of peritonsillar sepsis was higher in children with a history of recurrent tonsillitis. Needle aspiration of PTA resulted in a higher incidence of recurrence compared to incision and drainage. A management algorithm is suggested for the child presenting with peritonsillar sepsis.     

Biologic and physical characteristics of the non-peptidic, non-digitalis-like natriuretic hormone

At least three independent groups of natriuretic hormones have been isolated over the past ten years. Two, atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP), are proteins and the third is made up of digitalis-like substances (DLS). The present report concerns the isolation, substantial purification and biologic actions of an entirely different natriuretic hormone (NH) which appears to be steroidal in nature and an isomer of cortisone. The source of NH was uremic urine. Purification involved successive chromatographic steps including gel filtration and multiple HPLC runs through C-18 resins. A translucent crystal ultimately was obtained. The product was examined using mass spectroscopy with trimethylsilyl derivatization. Only one compound was identifiable. The characteristics of the molecule include: a molecular weight, 360.4; a molecular formula, C21H28O5; a steroidal nucleus; UV absorption at 220 and 290 nm; and intrinsic fluorescence. The onset of action occurs within minutes both in the rat and, as previously shown, in several in vitro systems including the frog skin, toad bladder, fibroblasts and renal tubular epithelial cells grown in culture and isolated perfused cortical collecting tubules. In contrast to DLS, NH has been previously shown not to cross react with digoxin antibodies. Moreover, when given to intact rats, it produces a profound natriuresis but little or no kaliuresis. In contrast to ANF and BNP the compound is active orally as well as intravenously. It is clearly different from cortisone, based both on its biologic and mass spectroscopic characteristics.     

Luminol-enhanced chemiluminescent response of human melanocytes and melanoma cells to hydrogen peroxide stress

Dementia is one of the most common organic mental syndromes, usually caused by Alzheimer's disease (AD) or vascular dementia (VD) or both. Regarding AD we review the state or the art of the cholinergic approach and discuss some future options regarding preventive and nonsymptomatic strategies. Therapy for VD will consist mainly in influencing and preventing cerebrovascular pathology, because operational criteria for the diagnosis have only recently been proposed and are being discussed widely. One of the crucial problems here lies in the distinction between VD and AD and the recognition that the two disorders may be coexistent more often than assumed; the role of white matter changes seems to be particularly important. The same goes for the recognition that AD ist not a single entity. The question of heterogeneity may be solved when different therapeutic strategies are found for different subtypes. The focus of future plans should be on preventive strategies combined with an early diagnosis.     

Agouti signaling protein inhibits melanogenesis and the response of human melanocytes to alpha-melanotropin

In mouse follicular melanocytes, the switch between eumelanin and pheomelanin synthesis is regulated by the extension locus, which encodes the melanocortin-1 receptor (MC1R) and the agouti locus, which encodes a novel paracrine-signaling molecule that inhibits binding of melanocortins to the MC1R. Human melanocytes express the MC1R and respond to melanotropins with increased proliferation and eumelanogenesis, but a potential role for the human homolog of agouti-signaling protein, ASIP, in human pigmentation has not been investigated. Here we report that ASIP blocked the binding of alpha-melanocyte-stimulating hormone (alpha-MSH) to the MC1R and inhibited the effects of alpha-MSH on human melanocytes. Treatment of human melanocytes with 1 nM-10 nM recombinant mouse or human ASIP blocked the stimulatory effects of alpha-MSH on cAMP accumulation, tyrosinase activity, and cell proliferation. In the absence of exogenous alpha-MSH, ASIP inhibited basal levels of tyrosinase activity and cell proliferation and reduced the level of immunoreactive tyrosinase-related protein-1 (TRP-1) without significantly altering the level of immunoreactive tyrosinase. In addition, ASIP blocked the stimulatory effects of forskolin or dibutyryl cAMP, agents that act downstream from the MC1R, on tyrosinase activity and cell proliferation. These results demonstrate that the functional relationship between the agouti and MC1R gene products is similar in mice and humans and suggest a potential physiologic role for ASIP in regulation of human pigmentation.     

Alterations in gene expression and signal transductions in human melanocytes and melanoma cells

The development of techniques to cultivate human primary melanocytes in vitro has provided the technical foundation for understanding the biology of this cell. Human melanocytes require various growth factors and agents for proliferation in vitro. These compounds activate two major signal transduction pathways: a calcium- and phospholipid-dependent (protein kinase C or PKC) pathway and a cyclic AMP (cAMP)-dependent (protein kinase A or PKA) pathway. Alterations in these signal transduction pathways coupled with changes in specific genes (protooncogenes, growth factors, and tumor suppressor genes) have been observed in human melanoma cells compared with normal melanocytes. Our own work indicates that loss in the expression of the PKC beta II isotype is a common, if not universal, alteration that occurs early in human melanocyte transformation. In this review, we concentrate on alterations in the signal transduction pathways in human melanocytes and melanoma cells and delineate how an understanding of these changes may allow us to understand the molecular mechanisms involved in human melanocyte transformation.     

Aromatization of androstenedione by cultured human fibroblasts

The conversion of (1, 2, 6, 7-3H)androstenedione to (3H)estrone was measured in fibroblast monolayers grown from biopsies of genital and nongenital skins obtained from 15 control subjects, 9 males with developmental defects of the urogenital tract, and 8 patients with hereditary male pseudohermaphroditism. Under the standardized conditions utilized in this study, the rate of estrone formation in the fibroblasts from normal controls varied from less than 0.2 to 5.5 pmol/100 mg protein/h, and these rates were enhanced by incubation of intact monolayers with choleragen, theophylline, or dexamethasone. Rates of estrone formation were higher in some foreskin strains grown from subjects with developmental defects of the urogenital tract and in strains from scrotum and foreskin of patients with familial incomplete male pseudohermaphroditism, types 1 and 2 than in normal strains or strains from patients with testicular feminization. The meaning of these apparent high rates of estrone formation is unclear.     

The effects of calcium and magnesium ions on the proliferation of normal human epidermal melanocytes

This paper reported an epidemiological investigation on human and animal infection to Eperythrozoon in 5 provinces. The results showed that Eperythrozoon infection existed in human as well an in animals in those provinces. Due to geographical variation, the infection rates were different. The infection rate was not associated with sex and age in human. The overall infection rate of different Eperythrozoonoses was higher than in healthy humans. The cases of Eperythrozoonoses among human and pig-herd were reported in this paper.     

Production of endothelin-1 by cultured human synoviocytes

Langerhans-cell histiocytosis (LCH) is a rare condition with a wide clinical spectrum and variable prognosis. Patients with multisystem LCH have been treated with a variety of agents but may develop resistant and progressive disease. Based on a preliminary encouraging report on the activity of 2 chlorodoxyadenosine in this disease, we administered this agent to a patient with LCH which was resistant to corticosteroids and etoposide. After 4 courses of treatment the patient achieved a complete remission which is currently ongoing for 12 months. 2 CdA appears to be effective in patients with resistant LCH and warrants investigation in previously untreated patients with poor risk disease.     

Uptake of triiodothyronine into cultured human muscle cells

The uptake of T3 was measured in cultured human muscle cells at 37 degrees C and pH 7.4 in a medium containing albumin and glucose. The initial up]take increased linearly when the total T3 concentration was varied from 10(-9) to 10(-4) M. At prolonged incubation time the uptake decreased to virtually zero in about 30 min. These data indicate a rapid passive transport mechanism of T3 and a fast equilibration of the cellular T3 with the surrounding medium. In agreement with these conclusions the efflux of T3 was rapid and the initial uptake was not altered by pre-incubation in a T3-containing medium.     

Effect of lipoproteins on cultured human mesangial cells

It was recently reported that low-density lipoprotein (LDL) promotes mesangial cell proliferation, and oxidized LDL is cytotoxic for mesangial cells. However, there have been few studies about the effects of other lipoproteins on mesangial cells. Accordingly, we investigated the effect of various lipoproteins on cultured human mesangial cells using 3H-thymidine (3H-TdR) incorporation and cell counting assays. We also investigated the levels of several cytokines in mesangial cell culture supernatants after stimulation by the lipoproteins. Addition of very-low-density lipoprotein (VLDL) at concentrations up to 100 micrograms/mL, intermediate-density lipoprotein (IDL) at up to 50 micrograms/mL, and LDL at up to 50 micrograms/mL induced the proliferation of cultured human mesangial cells, whereas cell growth was inhibited at higher concentrations. Oxidized LDL caused a concentration-dependent decrease of 3H-TdR incorporation. High-density lipoprotein (HDL) had no proliferative effective effect at any concentration. Exposure to VLDL, IDL, LDL, or a high concentration of HDL enhanced the secretion of interleukin-6, platelet-derived growth factor, and transforming growth factor-beta by mesangial cells, whereas tumor necrosis factor-alpha secretion was stimulated by oxidized LDL. These finding indicate that triglyceride (TG)-rich lipoproteins (VLDL and IDL) promote mesangial cell proliferation as well as LDL, whereas oxidized LDL has the reverse effect. These effects of lipoproteins may be related to modulation of various cytokines. Accordingly, TG-rich lipoproteins, LDL, and oxidized LDL may be involved in mesangial cell proliferation and injury in patients with mesangial proliferative glomerulonephritis.     

Argininosuccinate synthetase activity in cultured human lymphocytes

The activity of argininosuccinate synthetase (E.C. 6.3.4.5), a urea cycle enzyme, was measured in cultured human lymphocytes using a new radioactive assay. Control cells had a maximum specific activity of 15.7 +/- 8.7 nmoles per hour per milligram of protein and an apparent Km for citrulline of 2 X 10(-4) M, whereas cells derived from a patient with citrullinemia had no detectable activity. A nutritional variant, selected out of the citrullinemic lymphocyte population by ability to grow in citrulline, had a maximum specific activity of 10.7 +/- 3.8 nmoles/hr/mg and an apparent Km for citrulline of 2 X 10(-2) M. These measurements confirm the observation that citrullinemia is associated with a defect in argininosuccinate synthetase activity and provide further evidence that citrullinemia is expressed in cultured lymphocytes. The emergence of a nutritional variant with a partial defect in argininosuccinate synthetase enzyme suggests that this citrullinemic patient has a heterogeneous population of cells, some totally defective and others only partially defective in argininosuccinate synthetase. The new activity assay is described in detail.     

Lipid synthesis in cultured human embryonic fibroblasts

We describe here the pathways by which human embryonic fibroblasts synthesize lipids. In these studies, we quantitated the phospholipds by their phosphorus content and by their acyl components. These determinations defined both the chemical composition of the cellular membranes as well as their metabolic turnover. Using radiolabeled precursors, we have shown (a) synthesis of the glycerol moiety via glycolysis and the action of glycerokinase, (b) utilization of both exogenously added and endogenously synthesized fatty acids, (c) synthesis de novo of phosphatidyl choline and phsphatidyl ethanolamine from their base precursors, and (d) the methylation of phosphatidyl ethanolamine yielding phosphatidyl choline. Dividing cells synthesized phosphoglyceride more rapidly than cells in the stationary phase. However, considerable turnover of cellular lipid did occur in the stationary phase.     

Chimeric human epidermal reconstructs to study the role of melanocytes and keratinocytes in pigmentation and photoprotection

OBJECTIVE: To compare the ability of peripheral blood monocytes (PBM) and peritoneal macrophages (PM) to mediate the in vitro cytolysis of endometrial cells from eutopic and ectopic endometrium in women with endometriosis. DESIGN: Prospective study of immune function. SETTING: Institute for the Study and Treatment of Endometriosis and university-based research laboratories. PATIENT(S): Twenty-four women with endometriosis (15 in stage I/II, 9 in stage III/IV) and 4 patients treated with GnRH agonists. INTERVENTION(S): Peritoneal fluid and peripheral blood were sampled and eutopic and ectopic endometrium were biopsied during diagnostic laparoscopy. MAIN OUTCOME MEASURE(S): Lysis of autologous endometrial cells. RESULT(S): Peripheral blood monocytes were significantly more cytolytic than peritoneal macrophages against autologous uterine endometrial cells. However, PBM and PM displayed a similar degree of cytolysis against a hepatoma cell line. Ectopic endometrial cells were significantly more resistant to cytolysis by autologous PBMC than were matched eutopic endometrial cells, and were completely resistant to cytolysis by autologous PM. CONCLUSION(S): The reduced capacity of PM from women with endometriosis to mediate the destruction of endometrial cells coupled with the increased resistance of ectopic endometrial cells to macrophage-mediated cytolysis may facilitate the survival of these cells within the peritoneal cavity of women with endometriosis.     

Fibroblasts cultured from venous ulcers display cellular characteristics of senescence

PURPOSE: A well-recognized characteristic of venous ulcers is impaired healing. Fibroblasts cultured from venous ulcers (wound-fb) have been shown to have reduced growth rates and are larger than normal fibroblasts (normal-fb) from the ipsilateral limb. Reduced growth capacity and morphologic changes are 2 well-known traits of cellular senescence. Other molecular changes are overexpression of matrix proteins, such as cellular fibronectin (cFN), and enhanced activity of beta-galactosidase at pH of 6.0 (senescence associated beta-Gal, or SA-beta-Gal). Senescence, an irreversible arrest of cell proliferation with maintenance of metabolic functions, may represent in vivo aging and thus may be related to impaired healing. METHODS: Cultured normal-fb and wound-fb from 7 venous ulcer patients (average age, 51 years) were obtained by taking punch biopsies of the perimeter of the ulcer and from the ipsilateral thigh of the same patient. Growth rates, SA-beta-Gal activity, and level of cFN protein (immunoblot) and message (Northern blot) were measured. RESULTS: In all patients, wound-fb growth rates were significantly lower than those of normal-fb (P =.006). A higher percentage of SA-beta-Gal positive cells were found in all wound-fb (average, 6.3% vs. 0.21%; P =.016). The level of cFN, was consistently higher in all wound-fb tested. Also, in 4 patients, the level of cFN messenger RNA (mRNA) was increased. CONCLUSION: Fibroblasts cultured from venous ulcers exhibited characteristics associated with senescent cells. Accumulation of senescent cell in ulcer environment may be associated with impaired healing.