Discrimination of normal and transformed cells in vitro by cytologic and morphologic analysis

Malignant A-549 lung carcinoma and adenovirus-12 SV40 hybrid virus transformed non-tumorigenic human bronchial epithelial cells (BEAS-2B) were objectively discriminated from normal bronchial epithelial (BE) cells on the basis of Papanicolaou stained nuclear features (e.g. shape, chromatin texture, hyperchromasia) and nucleolar morphology (e.g. number per cell, irregular contours). Morphometric analysis indicated that significant differences in cellular morphology existed between BE, BEAS-2B, and A-549 cells. Similar analyses of transformed, tumorigenic cell lines demonstrated that nuclear features (i.e., chromatin texture, clearing of parachromatin, hyperchromasia, variation in thickness of the nuclear envelope, sharp indentations in the nuclear envelope), and nucleolar features (i.e., degree of roundness, presence of angular projections, number per cell) discriminated chemically and virally transformed cells from spontaneously transformed cells. Nuclear and nucleolar features were correlated with the growth rate of tumorigenic cell lines. These analytical approaches will be helpful in studies of the effects of various factors (e.g. vitamin A, phorbol ester, oncogene transfection) on cellular proliferation and/or differentiation.

Managing skin disease in resource-poor environments - the role of community-oriented training and control programs

Programs that have been devised to improve the lot of patients with skin disease, or disease presenting with skin signs and symptoms, in resource-poor regions have focused mainly on education and training or community-oriented control measures. However, both have in common an objective of managing disease at population level. Training has been delivered in different ways both by direct teaching for varying periods of time or by web-based and electronic communication; control measures have been less in evidence and there is a great need for more support from funding agencies. Despite this, there is now a growing number of successful initiatives in health improvement for skin conditions that cover many parts of the world. This report describes many of these schemes as an example of what can be done to help patients.

SUMO-modified nuclear cyclin D1 bypasses Ras-induced senescence

Oncogene-induced senescence represents a key tumor suppressive mechanism. Here, we show that Ras oncogene-induced senescence can be mediated by the recently identified haploinsufficient tumor suppressor apoptosis-stimulating protein of p53 (ASPP) 2 through a novel and p53/p19(Arf)/p21(waf1/cip1)-independent pathway. ASPP2 suppresses Ras-induced small ubiquitin-like modifier (SUMO)-modified nuclear cyclin D1 and inhibits retinoblastoma protein (Rb) phosphorylation. The lysine residue, K33, of cyclin D1 is a key site for this newly identified regulation. In agreement with the fact that its nuclear localization is required for its oncogenic activity, we show that nuclear cyclin D1 is far more potent than wild-type (WT) cyclin D1 in bypassing Ras-induced senescence. Thus, this study identifies SUMO modification as a positive regulator of nuclear cyclin D1, and reveals a new way by which cell cycle entry and senescence are regulated.

Interdigital lesions and frequency of acute dermatolymphangioadenitis in lymphoedema in a filariasis-endemic area

BACKGROUND

Lymphatic filariasis (LF) is a mosquito-borne nematode infection that causes permanent lymphatic dysfunction in virtually all infected individuals and clinical disease in a subset of these. One major sequel of infection is lymphoedema of the limbs. Lymphoedema of the leg affects an estimated 15 million persons in LF-endemic areas worldwide. Acute dermatolymphangioadenitis (ADLA) in people with filarial lymphoedema causes acute morbidity and increasingly severe lymphoedema. Episodes of ADLA are believed to be caused by bacteria, and it has been shown that entry lesions in the skin play a causative role. Clinical observations suggest that interdigital skin lesions of the feet, often assumed to be fungal, may be of particular importance.

OBJECTIVES

To investigate the epidemiology and aetiology of interdigital lesions (IDL) of the feet in filarial lymphoedema.

METHODS

The frequency and mycological aetiology of IDL in 73 patients with filarial lymphoedema were compared with 74 individuals without lymphoedema in a region of Guyana highly endemic for Wuchereria bancrofti.

RESULTS

More than 50% of patients with lymphoedema had one or more IDL (odds ratio 2.69; 95% confidence interval 1.31-5.66; P<0.005 compared with controls). The number of lesions was the strongest predictor of frequency of ADLA. Only 18% of the lesions had positive microscopy or culture for fungi (dermatophytes and Scytalidium).

CONCLUSIONS

These findings highlight the importance of interdigital entry lesions as risk factors for episodes of ADLA and have implications for the control of morbidity from filarial lymphoedema.

Literature review. Onychomycosis

Onychomycoses have been divided into several categories depending on the site of nail penetration by the fungus. However, not all cases entirely fit with this classification, such as potentially the deep spread of superficial fungi, suggesting alternative penetration routes. A recent European study showed that the prevalence of onychomycosis may be as high as 26.9%. The main causative agent varies according to climate; dermatophyte infections are common worldwide (70% in Europe). Mycological examination is currently the preferred diagnostic method, despite a false-negative rate of 30%. A clinical diagnostic aid that can be used alongside mycological tests is currently being developed. Newer diagnostic approaches include calcofluor, which stains fungi in nails, and molecular genetic techniques for species recognition (e.g. RFLP). Restriction fragment length polymorphism (RFLP) can also distinguish between failed treatment and reinfection. Onychomycosis can be treated with numerous oral and topical agents alone or in combination. In some studies, combination therapy appears more effective than monotherapy.

Pharmacoeconomics--an aid to better decision-making

OBJECTIVES

The first aim of this workshop was to define pharmacoeconomic concepts and terminology. Pharmacoeconomics can be defined as the branch of economics that uses cost-benefit, cost-effectiveness, cost-minimization, cost-of-illness and cost-utility analyses to compare pharmaceutical products and treatment strategies. Economic evaluations provide healthcare decision-makers with valuable information, allowing optimal allocation of limited resources. However, pharmacoeconomics is based on long-term benefits, whereas physicians are typically forced to seek immediate savings. The second aim was to review pharmacoeconomic studies in the field of onychomycosis and finally to discuss future perspectives.

RESULTS AND CONCLUSIONS

We discussed current pharmacoeconomic issues on the management of onychomycosis. Consensus was reached on the following issues: * Published pharmacoeconomic studies concerning onychomycosis are flawed. Future studies should be based on internationally validated principles and appropriate models. The fact that costs of different drugs, laboratory examinations and physician visits vary worldwide should be considered. Cost-benefit studies are required. * The National Institute for Clinical Excellence (NICE) recommendations are often considered in countries other than the UK, even when not adapted to the country in question. * Generic drugs might reduce costs, but this depends on their effectiveness (bioavailability). * Sampling requests affect the economic cost (dependent on methodology, which depends on country) and physicians often trust their instincts even when tests are repeatedly negative. * The cost of adverse event management is usually considered to be 10%; this may be too high for onychomycosis, as treatments are relatively safe without severe side-effects. * Probability of recurrence for each drug should be determined. * Need for disease severity standardization, definition of diagnostic criteria and successful treatment (mycological and clinical cure).

A guide to antibiotic resistance in bacterial skin infections

The emergence of bacterial resistance to commonly used antibiotics is not new. In this review we have tried to cover the ever increasing problems facing the treatment and containment of bacterial skin infections. We have tried to give an overview of the varied mechanisms by which bacteria gain and spread antimicrobial resistance, whilst dealing with the patterns of resistance exhibited by some of the commonly encountered organisms. Where there is evidence, we have formulated an approach on how to tackle antibiotic resistance. Where there is a lack of evidence we have formulated what we perceive to be appropriate guidelines.

Patients at risk of onychomycosis - risk factor identification and active prevention

OBJECTIVES

The aims of this workshop were to identify risk factors for onychomycosis and to reach consensus on the management of high-risk groups to allow the development of guidelines to help doctors recognize risk factors that complicate treatment.

RESULTS AND CONCLUSIONS

Previous Trichophyton rubrum infection, older age, abnormal nail morphology, immunodeficiency and genetic factors were identified as risk factors for initial infections. Risk factors for recurrence (relapse and re-infection) are largely the same. The experts agreed that the prevention of onychomycosis and its recurrence should be based on the correct treatment of tinea pedis, screening family members and adequate patient education. In addition, generic management recommendations for each high-risk group were discussed: * Immunosuppressed patients Usual dose and treatment length not appropriate Follow-up required Beware of drug interactions * Diabetics Prophylactic foot care combined with nail treatment Good opportunity for patient education, footwear, foot care, etc. Beware of drug interactions * Psoriatics and patients with abnormal nails Dermatophyte eradication does not restore normal nails * Children High failure rate possibly due to compliance problems.

Definition of an algorithm for the management of common skin diseases at primary health care level in sub-Saharan Africa

In order to help primary health care (PHC) workers in developing countries in the care of common skin diseases, an algorithm for the management of pyoderma, scabies, superficial mycoses, contact dermatitis and referral of early leprosy cases (based on the identification of diseases through the presence of objective key signs, and on treatments by generic drugs) was elaborated. One thousand patients were seen by trained dermatologists, who established diagnoses and treatments; in addition, there was systematic recording of each key sign, according to the successive algorithm steps. We compared the diagnostics and treatments obtained for several combinations of diagnostic signs, with those of the dermatologists. Sensitivity, specificity, positive predictive value and negative predictive value of defined combinations were high for pyoderma, scabies and superficial mycoses. Values were less exact for dermatitis and leprosy, but were considered sufficient for the level of health care targeted. The apportionment of treatments between the algorithm and the dermatological approaches was considered appropriate in more than 80% of cases; mismanagement was possible in 7% of cases, with few predictable harmful consequences. The algorithm was found satisfactory for the management of the dermatological priorities according to the standards required at the PHC level.

Cytokine production and lymphocyte proliferation in patients with Nocardia brasiliensis actinomycetoma

IFN-gamma, TNF-alpha, IL-4, IL-10 and IL-12 concentrations in the supernatant of peripheral blood mononuclear cell (PBMC) cultures and the in vitro proliferation of PBMC were studied in 25 patients with actinomycetoma caused by Nocardia brasiliensis and in 10 healthy controls from endemic zones. Cell cultures were stimulated by a N. brasiliensis crude cytoplasmic antigen (NB) and five semi-purified protein fractions (NB2, NB4, NB6, NB8, and NB10) separated by isoelectric. Phytohemagglutinin (PHA) and purified protein derivative (PPD) of Mycobacterium tuberculosis were used as control antigens. Skin tests were performed by injecting 0.1 ml of candidin and PPD intradermally (ID). Patients showed a poor response to tuberculin, while their response to candidin was more than two fold greater than that observed in the controls. Cell proliferation showed no statistically significant differences in either group. IFN-gamma production was higher in the healthy controls than in the patients, whereas TNF-alpha secretion was slightly higher in the patients' cultures. IL-4 was detected in the patients' cultures but not in the controls. IL-10 and IL-12 were present at low concentrations in both groups. These results suggest that patients with actinomycetoma show normal antigen recognition, but with low IFN-gamma production, and higher concentrations of IL-4, IL-10 and TNF-alpha in the patients' PBMC cultures, indicating that they probably have a Th2 type of immune response.

Superficial white onychomycosis revisited

BACKGROUND

Superficial white onychomycosis (SWO) is a distinct pattern of fungal nail invasion, which is usually treated with topical antifungals.

OBJECTIVE

This paper presents a case of SWO with deep penetration and records other similar cases.

METHODS

The clues to deep invasion of the nail plate are twofold: an inability to clear the discoloration by scraping the nail and a clinical involvement of the nail plate in the proximal nailfold area. Histology of the nail keratin will confirm deep penetration beyond the superficial layers of the nail plate.

RESULTS

In the light of this finding the authors propose a further subdivision of SWO to reflect previously unrecognized variants with therapeutic implications into: (i) the classical SWO type; (ii) the dual invasion of the nail plate, superficial and ventral; and (iii) the pseudo-SWO with deep fungal invasion of the nail plate.

CONCLUSIONS

This subdivision of SWO allows the clinician to treat the patient appropriately using topical antifungals when the disease is restricted to the dorsum of the nail. Systemic drugs either in isolation or in combination with topical treatment are mandatory when deep penetration or ventral fungal invasion are observed.

The International Foundation for Dermatology: an exemplar of the increasingly diverse activities of the International League of Dermatological Societies

The International Foundation of Dermatology (IFD) was established by the International League of Dermatology Societies to promote the care of skin disease in the developing world. Starting from an initial base of the Regional Dermatology Training Centre in Tanzania it has successfully trained a cadre of clinical officers and dermatology residents from different African countries. It has now broadened this approach to an assessment of the effectiveness of focused training in Mali. The IFD is also completing a global assessment of dermatological needs in developing countries with a view to establishing guidelines and programmes for the control of common skin diseases. An ongoing strategy has been to work with other agencies to help ease the burden of other endemic tropical diseases that affect the skin; preventing the development of elephantiasis in filarial lymphoedema has been one such project implemented through a programme of skin hygiene.

High prevalence of foot diseases in Europe: results of the Achilles Project

OBJECTIVE

To provide an insight into the prevalence of foot disease in Europe, and to include an assessment of the prevalence of predisposing factors and their correlation with foot disease.

DESIGN

Large population-based survey conducted in 16 European countries.

SETTING

The project consisted of two parts (study I and study II), in which all patients presenting to general practitioners and dermatologists over a defined time period were invited to participate. Patients. In study I, 70,497 patients presenting to dermatologists or general practitioners were recruited, and in study II 19,588 patients presenting to dermatologists were recruited.

MAIN OUTCOME MEASURE

The feet of all participants were examined for signs of foot disease. The assessors also recorded relevant details such as the age and sex of patients, and the presence of predisposing factors for foot disease. In addition, patients in study II were offered a free mycological examination of the toenails and skin on the feet.

RESULTS

In study I, 57.0% of patients had at least one foot disease. In study II, 61.3% had at least one foot disease. The proportions of patients with fungal foot disease and non-fungal foot disease in study I were 34.9% and 38.4%, respectively, and in study II were 40.6% and 41.7%, respectively. Orthopedic conditions and metatarsal corns were the most frequently reported non-fungal foot diseases, and onychomycosis and tinea pedis were the most frequently observed fungal infections.

CONCLUSIONS

This large-scale survey suggests that the prevalence of fungal and non-fungal foot disease is higher than previously estimated.

Mycobacterium abscessus: a cutaneous infection in a patient on renal replacement therapy

We report a 72-year-old man on haemodialysis who presented with multiple abscesses on his lower legs. Routine bacterial culture of abscess pus was reported as 'sterile' after 48 h, leading to the suspicion of a mycobacterial infection. Skin biopsy taken for mycobacterial microscopy and culture isolated a heavy growth of Mycobacterium abscessus.

[Antenatal diagnosis of limb body wall complex]

The "limb body wall complex" or LBWC is a rare polymalformative syndrome. Two distinct phenotypes of which were recently described: one form with "placento-cranial" adhesion and the other with "placento-abdominal" adhesion. Coelosomia is found in all cases, it variably coexists with encephalic, vertebral, visceral or limb anomalies. Three pathogenesis are proposed: the "early amnion rupture" theory and the "vascular" theory can explain the form with "placento-cranial" adhesion, conversely, the "defective folding process" allows for a better explanation of the form with "placento-cranial" adhesion. These theories do not exclude each other if we accept that this syndrome could be split: the first form would then be the original "LBWC" et could belong to "amniotic band syndrome", the mechanism of which is not precisely known, whereas the second could be named "body stalk syndrome" - "syndrome du cordon court". In any case, this syndrome should be better known so as to be studied and give a prognosis for a later pregnancy, because there is no recurrence.

Analysis by enzyme-linked immunosorbent assay and immunoblot of the antibody responses of patients infected with Mycobacterium marinum

The serum antibody responses of a total of 14 patients with active or recently cured Mycobacterium marinum infections were analysed via a combination of enzyme-linked immunosorbent assay (ELISA) and the immunodevelopment of Western blots of M. marinum antigen. Normal human sera and sera from patients with active pulmonary tuberculosis were also analysed as controls. The detectable IgG response of M. marinum patients, as demonstrated by ELISA, was highly variable and did not differ significantly from normal controls. IgA and IgM levels were generally low in the M. marinum patients and were not significantly different from normal controls. Immunodevelopment of Western blots of M. marinum antigen with the sera of patients with M. marinum infections revealed that a number of antigens were recognised. Of particular note was an 18-kDa species that was recognised by 11 out of 14 patients (and by none of the normal controls). The 18-kDa antigen may be a useful serodiagnostic marker in the identification of M. marinum infections.

Can school teachers improve the management and prevention of skin disease? A pilot study based on head louse infestations in Guerrero, Mexico

BACKGROUND

The effect of health education provided by teachers, in three primary schools of Guerrero, Mexico, on the prevalence of head louse infestation was compared.

METHODS

A cross-sectional survey and rapid appraisal methods were performed, including a child questionnaire and qualitative data from teachers and focus groups of mothers in the same schools.

RESULTS

Nine hundred and forty-four students and 33 teachers were interviewed; a focus group discussion with 6-8 mothers per school was performed. In the self-diagnosis of pediculosis, the prevalence was 22% (range, 18%-33%) with a sensitivity of 68% and a specificity of 86%. In one school, 100% of the teachers applied a health program, whereas in the other two schools this percentage was only 20%. A child under 9 years of age who attended a school without information on health was 3.6 times more likely to have head louse infestation (OR = 3.6, CI 95% = 2.1-6) than a child of the same age who attended a school where information was given. In older children the effect and potential impact were lower. The difference between the two age groups is unlikely to be explained by chance (X2 het = 5.7, df = 1, p = 0.01).

CONCLUSIONS

This study emphasizes the potential value of simple, but effective, health education provided by school teaching staff through liaison with patents in the amelioration of endemic disease.

Cerebellar vermis measurement at cranial sonography for assessing gestational age in the newborn weighing less than 2000 grams

Prognosis of the very low birth weight infant depends more on gestational age than birth weight, but clinical assessment of gestational age of very low birth weight infants is inaccurate. We wished to determine how well cerebellar vermis dimensions might predict gestational age in infants of birth weight less than 2000 g. We obtained suitable midline sagittal images of the cerebellar vermis at cranial sonography, performed via the anterior or posterior fontanelle, in 41 infants, from the regional neonatal intensive care unit whose gestational age was known. We measured the cerebellar vermis area and diameter on the hard-copy image provided the margins of the vermis were clearly visible, the cerebellar tonsils were excluded from the image, and the anterior and posterior divisions of the corpus medullare were visible on the image. Vermis diameter was measured from the base of the fourth ventricle to the junction of folium and tuber vermis. Vermis area was calculated using a stereological method using a test system of regularly spaced points randomly placed over a magnified image of the cerebellar vermis. We generated regression equations for estimating gestational age using combinations of birth weight, vermis area, or vermis diameter for the 26 infants with birth weight of less than 2000 g for whom the cerebellar vermis measurements were obtained within one week of birth. Vermis area and diameter correlated very highly. They both can be used for predicting gestational age. The addition of either vermis area or diameter to birth weight improves accuracy of gestational age assessment. If birth weight was presumed to be unknown, cerebellar vermis area or diameter allow prediction of gestational age to within +/- 1.3 weeks (1 standard error) or +/- 2.5 weeks, using a 95% prediction interval. If the same method of reporting is applied to the New Ballard Score, the New Ballard Score predicts gestational age +/- 1.7 weeks (1 standard error) or +/- 3.4 weeks, using a 95% prediction interval.

Posterior fontanelle cranial ultrasound: anatomic and sonographic correlation

OBJECTIVE

The purpose of this study was to correlate normal brain anatomy as seen on posterior fontanelle cranial sonography with anatomical sections of the premature infant brain.

MATERIALS AND METHODS

Images obtained from 93 cranial ultrasound examinations performed via both the anterior and posterior fontanelle in 53 infants, ranging in gestational age from 24 to 42 weeks, were reviewed to determine the ultrasound anatomy visible and also the changing appearances with increasing gestational age. The brains of five infants were sectioned at post-mortem according to predetermined anatomical landmarks to correlate with posterior fontanelle ultrasound scan planes. Brain preservation techniques involved fixation in formalin at room temperature, refrigeration of brain following formalin fixation, and brain freezing at -17 degrees C.

RESULTS

In the premature infant brain, the subarachnoid space is up to 15 mm in thickness. Occipital lobe anatomy well seen includes occipital horns of lateral ventricles, and white matter tracts to the visual cortex and visual association areas. Brain anatomy was better appreciated on sections obtained following brain freezing rather than formalin fixation.

CONCLUSION

Satisfactory ultrasound anatomic correlation of the premature brain is possible using a brain freezing preservation technique. Posterior fontanelle ultrasound allows detailed illustration of occipital lobe anatomy.

Immunohistochemical detection of a novel 22- to 25-kilodalton glycoprotein of Paracoccidioides brasiliensis in biopsy material and partial characterization by using species-specific monoclonal antibodies

Two murine monoclonal antibodies (MAbs) specific to Paracoccidioides brasiliensis (as determined by enzyme-linked immunosorbent assay [ELISA] and Western blot [immunoblot]) were produced by using a modification of standard hybridization protocols, with cyclophosphamide included as an immunomodulator to abolish responses to highly cross-reactive immunodominant epitopes. MAbs PS14 and PS15 are two different clones which exhibit similar characteristics by ELISA and Western blot. They are directed against a 22- to 25-kDa antigen which is present in P. brasiliensis and which could not be identified in other dimorphic fungi by ELISA or Western blot. Partial purification of the antigen was accomplished by isoelectric focusing, and deglycosylation studies suggested that the 22- to 25-kDa antigen is a glycoprotein with a pI of between 4.5 and 5 and that O-linked sugars may be part of the recognized epitope. The MAbs stained the cytoplasm of P. brasiliensis yeast and hyphal cells in cryostat sections of fresh cultures of the fungus. In addition, the MAbs stained the wall of paracoccidioidomycotic granulomas, as well as the cytoplasm of the fungus, as determined by the use of immunofluorescence, immunoperoxidase, and immuno-alkaline phosphatase staining techniques in paraffin-embedded sections of human biopsy material, and they failed to stain granulomas resulting from other clinical conditions. These findings suggest that these MAbs have potential use in the immunohistochemical identification of P. brasiliensis.

Histoplasmosis of the central nervous system

Histoplasma capsulatum infection of the central nervous system is extremely rare in the United Kingdom partly because the organism is not endemic. However, because the organism can remain quiescent in the lungs or the adrenal glands for over 40 years before dissemination, it increasingly needs to be considered in unexplained neurological disease particularly in people who lived in endemic areas as children. In this paper a rapidly progressive fatal myelopathy in an English man brought up in India was shown at necropsy to be due to histoplasmosis. The neurological features of this infection are reviewed.

[Regulation of sterol carrier protein-2 in human luteal cells by LH and LH-RH]

Conversion of cholesterol to pregnenolone is the most important and, at the same time, the rate-limiting step of steroidogenesis. Sterol carrier protein-2 (SCP2) or nonspecific lipid transfer protein (nsL-TP) is an intracellular protein, which plays an important role in the pre- and transmitochondrial transport of cholesterol and for the mitochondrial synthesis of pregnenolone. Synthesis of pregnenolone in rat Leydig cells can be increased by LH and LH-RH; however, only LH leads to characteristic changes in intracellular concentrations of SCP2. This means that synthesis of pregnenolone is regulated in two different ways. In this study we aimed to find out whether such a 'second way' of steroidogenesis is also demonstrable for the human corpus luteum (i.e. human luteal cells). Human luteal cells were collected during follicle punctures and were cultured as described previously. We demonstrate that (human) LH/hCG are able to enhance pregnenolone synthesis; this process is accompagnied by typical changes of SCP2 and an increase in activity of 7-dehydrocholesterol reductase, which is a marker enzyme for SCP2. LH-RH was shown to exert no effect. Thus, we conclude that a second way of steroidogenesis (i.e. synthesis of pregnenolone) cannot be proved for the human corpus luteum.

Monoclonal antibodies to periodontal ligament cells

Ten mouse monoclonal antibodies were prepared against cultured bovine periodontal ligament cells to be used as reagents for the study of periodontal disease and wound healing. Using standard immunohistochemical methods, these antibodies were found to recognize cell surface antigens in formalin-fixed bovine periodontium. Three of the 10 monoclonal antibodies (i.e., PDL-1, PDL-2, and PDL-10) cross-reacted with cells found in primate periodontium. While the isolated monoclonal antibodies appeared to distinguish subpopulations of cells located in the supporting tissues of teeth, immunohistological examination of other organs (dermis, kidney, skeletal muscle, thyroid, and parotid gland) indicated that a number of cell types of mesenchymal origin share an antigen(s) found on periodontal cells. The monoclonal antibodies described in this report should prove to be useful in studies of periodontal disease and guided tissue regeneration by providing both analytical reagents and immunochemical methods for isolating selected cell populations of the periodontium.

Biogenesis of plasma lipoproteins in rat hepatoma McA-RH7777: importance of diffusion-mediated events during cell growth

Cultured McA-RH7777 rat hepatoma cells actively synthesize and secrete plasma lipoproteins. However, synthesis of [14C]triglyceride declines monotonically throughout the early growth period and remains low in postconfluent cultures; and net secretion of [14C]triglyceride is 10-fold more efficient in logarithmically growing cultures than in postconfluent cultures. Secretion of apolipoproteins associated with very low density and low density lipoproteins is selectively reduced in postconfluent cultures. The temporal reductions in [14C]triglyceride production are related more strongly to increasing cell concentration (cells/cm3 medium) than to increasing cell density (cells/cm2 growth surface). We have allowed cells to grow either retained within small circular corrals or unrestricted in culture dishes. When seeded at equal density (10(4) cells/cm2) but at one-fifth the cell concentration, corralled cells synthesize twice as much [14C]triglyceride per cell after 2 and 4 d, and are 10 times as efficient in [14C]triglyceride secretion by 6 d of growth, as noncorralled cells. When seeded at equal cell concentration (10(5) cells/dish) but at 5 times the cell density, corralled cells are only 20% less efficient at [14C]triglyceride synthesis and secretion than noncorralled cells. Conditioned medium depresses synthesis and secretion efficiency of [14C]triglyceride. Orotic acid exposure also inhibits synthesis of [14C]triglyceride and secretion of certain [35S]apolipoproteins in early cultures, but it has no significant effect on late cultures. We conclude that diffusion-mediated events are important regulators of triglyceride and apolipoprotein production in growing rat hepatoma cells, but that events associated with formation of cell-to-cell contacts play a minor role in regulation of plasma lipoprotein biogenesis.

Failure of a dengue 1 sub-unit vaccine to protect mice against a lethal dengue virus infection

Mice immunized with DEN-1 pre-matrix protein produced antibody which reacted with dengue virus infected cells and intact virions but failed to neutralize virus in vitro or in vivo. Newborn mice passively immunized with anti-DEN-1 pre-matrix antibody also failed to survive intracerebral infection with 100 LD50 of any dengue virus serotype.

Apolipoproteins of the orotic acid fatty liver: implications for the biogenesis of plasma lipoproteins

Rats fed orotic acid develop fatty livers characterized by triglyceride-laden, membrane-bounded vesicles designated "liposomes." We have measured the levels of apolipoproteins in isolated liposomes and other subcellular fractions by SDS-polyacrylamide gel electrophoresis, electrotransfer, and immunodecoration. Apolipoproteins Bh, Bl, E, and C appear to cofractionate; for these proteins, the liposomal pool represents a large portion of their total intracellular mass. However, liposomes are deficient in both variants of apoB relative to apoE and apoC when compared with rat plasma very low density lipoprotein (VLDL). Albumin and apolipoproteins A-I and A-IV are also found in liposomes, but this organelle represents a minor fraction of their total intracellular mass. The liposomal apolipoproteins show varying degrees of association with cisternal lipid and with organelle membranes. Orotic acid may selectively block VLDL production at the level of particle assembly or transorganellar movement. We conclude that liposomal contents probably represent exaggerated accumulations of VLDL assembly intermediates, and that the intracellular partitioning of high density lipoprotein-destined from VLDL-destined components occurs at an early stage in particle biogenesis. Moreover, some unique structural feature of apoB may effect movement of VLDL assembly intermediates through secretory organelles.

Purification and characterization of the pore forming protein of yeast mitochondrial outer membrane

One of the major outer membrane proteins of yeast mitochondria was isolated and purified. It migrated as a single band with an apparent molecular weight of 30 kDa on a SDS-electrophoretogram. When reconstituted in lipid bilayer membranes the protein formed pores with a single channel conductance of 0.45 nS in 0.1 M KCl. The pores had the characteristics of general diffusion pores with an estimated diameter of 1.7 nm. The pore of mitochondrial outer membranes of yeast shared some similarities with the pores formed by mitochondrial and bacterial porins. The pores switched to substates at voltages higher than 20 mV. The possible role of this voltage-dependence in the metabolism of mitochondria is discussed.

Light and electron microscopic features of tropical ulcer

The histopathological features of 20 tropical ulcers with the electron microscopic findings on seven biopsy specimens are reported. The main findings were loss of epidermis associated with extensive dermal oedema, infiltration by polymorphonuclear leucocytes, and disruption of collagen bundles. The presence of micro-organisms at the site of tissue damage was shown and compared with the morphology of the organisms grown in culture. The most commonly identified bacteria were pleomorphic rods whose electron microscopic appearances accorded most closely with Fusobacteria grown in vitro. Spirochaetes, identified ultrastructurally as Treponema sp, were also present. There was no evidence of vasculitis to explain the rapid onset of ulceration, but necrotic changes seen in the dermis and the inflammatory cell infiltrate suggest that, associated with cell necrosis, bacteria previously shown in vitro have an important role in the pathogenesis of tropical ulcers.