Controlled management of public relations following a public health incident

This paper describes the management of public relations following an outbreak of multidrug resistant TB at a London hospital. Eight patients were involved, all of the secondary cases occurred in HIV seropositive patients, and three cases died. The paper describes how the the Incident Committee undertook to recall contacts of the cases for screening, inform the general practitioners of all of the contacts about their patients' exposure, warn other organizations and professionals interested or involved in the management of HIV in the London area as to the nature of the incident, and establish a helpline, before informing a wider audience through the EPINET, Communicable Disease Report and national press.

Lipoperoxidase activity of Pityrosporum: characterisation of by-products and possible rôle in pityriasis versicolor

Modification of pigmentation and damage of melanocytes are characteristic features of skin colonisation of Pityrosporum orbiculare hyphae in pityriasis versicolor (PV). The yeast is lipophylic and lipid-dependent, capable of oxidising unsaturated lipid components of skin surface, i.e., unsaturated fatty acids, cholesterol and squalene (SQ). The oxidation of unsaturated fatty acids gives rise to dicarboxylic acids (DA) which behave, in vitro, as competitive inhibitors of tyrosinase. In this work, we further investigate the oxidase activity of Pityrosporum in vitro, by evaluating (a) the generation of lipoperoxides in cultures supplemented with fatty acids at various degrees of unsaturation; (b) the mechanism of SQ oxidation; (c) the chemical characteristics of some by-products of lipoperoxidation; (d) the formation of peroxisomes in fungal cells. In cultures supplemented with the saturated palmitic acid (C16:0) and monounsaturated oleic acid (C18:1 n-9), low amounts of lipoperoxides were detected by a spectrophotometric test, whereas in cultures supplemented with di-unsaturated linoleic acid (C18:2 n-6), significant concentrations were found. Gas chromatography-mass spectrometry analyses showed the generation of linoleic acid hydroperoxides both in Pityrosporum cultures and following incubation of acetone powder of the fungus with the unsaturated fatty acid, indicating the presence of a lipoxygenase activity in the fungus. In cultures supplemented with linoleic acid plus SQ, and increase of lipoperoxide generation was observed and trans-trans farnesal and squalene epoxides have been identified. Electron microscopic examinations have evidenced peroxisomes in cells grown in the presence of linoleic acid, whereas they were not detected in cultures supplemented with oleic acid and palmitic acid. The metabolic activities of peroxisomes, through the formation of hydrogen peroxide and the subsequent generation of hydroxyl radicals, may account for the peroxidation of SQ, which is not a substrate of lipoxygenase. Following these results, we propose a mechanism for DA generation by Pityrosporum metabolism and hypothesize that the lipoperoxidation process induced by lipoxygenase activity of the fungus may be the key to understanding the clinical appearance of skin manifestation of PV.

Growth and detection of filamentous fungi in the BacT/Alert blood culture system

Little is known about the behaviour of filamentous fungi in most blood culture systems, despite their increasingly recognised role in infections of immunocompromised hosts. The ability of the BacT/Alert system (Organon Teknika, Durham, North Carolina, USA) to detect the growth of 19 such fungi was examined. Eleven species grew and were detected rapidly; two species did not grow. Six species grew slowly, and were generally only recovered with terminal subculture after prolonged incubation. The CO2 production graph for some of these fungi showed a slow but steady rise, insufficient to cause the apparatus to signal positive. These results show that the BacT/Alert system may miss some fungi, either because of no growth in the medium or undetected slow growth. The latter problem could be overcome by prolonged incubation and terminal subculture when fungal infection is considered likely. Alteration of the signalling mechanism might permit earlier detection of some slow growing fungi.

Cutaneous Mycobacterium kansasii infection: case report and review

A case of cutaneous Mycobacterium kansasii infection is reported, and 28 similar cases are reviewed. Cutaneous infection may resemble sporotrichosis and is often associated with systemic illness, immunosuppression, skin pathology, or contact with contaminated water. Immunosuppressed patients with M. kansasii infection may present with atypical clinical features (such as cellulitis and seroma) and atypical histology (absence of granulomas), which may delay diagnosis and effective treatment. The incidence of disseminated M. kansasii infection, which has a worse prognosis, is higher among immunosuppressed patients. When M. kansasii infection is confined to the skin, the disease is usually indolent. Chemotherapy with a variety of agents, including traditional antituberculous agents as well as erythromycin, minocycline, and doxycycline, has been successful, although in vitro resistance to isoniazid and p-aminosalicylic acid is common. Reducing the dose of corticosteroids may be a beneficial adjunct to therapy for M. kansasii infection.

Lipoprotein(a) and treatment of chronic renal disease

OBJECTIVES

To compare lipoprotein(a) [Lp(a)] and albumin concentrations in patients with chronic renal disease receiving different forms of treatment and to determine, if any, the relationship between these variables.

DESIGN

A prospective cross-sectional, case-controlled study.

SETTING

A tertiary referral nephrology and dialysis unit.

SUBJECTS

Forty-four consecutive non-diabetic patients with chronic renal failure treated by renal transplantation (n = 18), haemodialysis (n = 18), continuous ambulatory peritoneal dialysis (CAPD; n = 8), and 30 healthy controls from subjects drawn from University personnel were studied.

INTERVENTIONS

Fasting morning venous blood was analysed for Lp(a), albumin, total cholesterol and glucose concentrations.

MAIN OUTCOME MEASURES

Comparison of plasma levels of these variables between the sub-groups.

RESULTS

Concentrations (median; 95% CI) of Lp(a) were significantly (P < 0.05) higher (38.4 mg dl-1; range 15.4-72.0) and of albumin lower (31.6 g l-1; range 28-35.2) in the CAPD group compared with both control subjects and other groups of chronic renal disease patients.

CONCLUSIONS

The elevated Lp(a) concentrations seen only in association with reduced albumin concentrations in CAPD patients suggest a regulatory role for albumin with albumin losses stimulating production of Lp(a).

Contact urticaria due to the common stinging nettle (Urtica dioica)--histological, ultrastructural and pharmacological studies

A frequent cause of contact urticaria is skin exposure to the common stinging nettle (Urtica dioica). The urticaria is accompanied by a stinging sensation lasting longer than 12 h. Little is known of the cellular and molecular mechanism of stinging-nettle urticaria. After preliminary pharmacological analysis of pro-inflammatory activity in nettle stings, the cellular response of mononuclear cells, polymorphonuclear cells and mast cells was examined in six people 5 min and 12 h after nettle contact. Only mast cell numbers were significantly increased at 12 h. Ultrastructurally, some mast cells showed evidence of degranulation at 5 min and 12 h. At 12 h mast cells were closely associated with dermal dendritic cells and lymphocytes suggesting a functional unit. The mean histamine and serotonin contents of a nettle hair were found to be 6.1 ng and 33.25 pg, respectively. Nettle-sting extracts did not demonstrate histamine release from dispersed rat mast cells in vitro. These results suggest that part of the immediate reaction to nettle stings is due to histamine introduced by the nettle. However, the persistence of the stinging sensation might suggest the presence of substances in nettle fluid directly toxic to nerves or capable of secondary release of other mediators.

Mechanism of antitumoral activity of catechols in culture

Cell lines Raji and K 562, lacking tyrosinase, and two melanotic human melanoma cell lines (IRE 1 and IRE 2), were exposed to concentrations from 5 X 10(-3) M to 10(-5) M of different phenols which are substrates of tyrosinase, i.e. l-dopa, dopamine, hydroquinone, terbutylcatechol, and of phenols which are not substrates of the tyrosinase, i.e. resorcinol, butylated hydroxyanisole and hydroquinone dimethyl ether. Cultures were carried out in the presence or in the absence of oxygen radical scavenger enzymes superoxide dismutase, catalase and peroxidase. The stability of each substance in culture medium was assayed by high performance liquid chromatography (HPLC). Results showed that: catechols which are substrates of tyrosinase decompose fully after 24 hr in medium; they are equally toxic for melanoma and non-melanoma cell lines; their toxicity increases when they are preincubated in medium for 24 hr and 48 hr before addition of cells; their toxicity is significantly reduced by addition of scavenger enzymes; on the contrary, phenols not substrates of tyrosinase are stable in medium and their toxicity is not reduced by scavenger enzymes. It is concluded that tyrosinase does not play a major role in catechol toxicity in vitro, which is probably due to some products of catechol decomposition, especially oxygen radicals, acting outside the cells.

Antimitochondrial effect of saturated medium chain length (C8-C13) dicarboxylic acids

In isolated rat liver mitochondria, respiration was competitively inhibited by medium chain length (C8 to C13) dicarboxylic acids to different extents: the higher the number of carbon atoms up to C12, the greater the inhibition. In particular, experiments on submitochondrial particles showed that the competitive inhibition concerned the following enzymes: NADH dehydrogenase, succinic dehydrogenase and reduced ubiquinone: cytochrome c oxido-reductase. These results tend to confirm the suggestion that the melanocytotoxic effect of dicarboxylic acids, which are also competitive inhibitors of tyrosinase, may be primarily due to an antimitochondrial effect rather than being tyrosinase-dependent.

Beneficial effect of 15% azelaic acid cream on acne vulgaris

Patients treated with azelaic acid (15%) cream for chloasma reported simultaneous improvement of acne lesions within the treated areas. This prompted an open study of its effect in cases of acne without chloasma. One hundred patients with acne vulgaris were treated for 3-9 months by twice-daily application of the cream with significant improvement in every case.

Ultrastructural and biochemical observations on the effect of 4-hydroxyanisole plus tyrosinase on normal human melanocytes and keratocytes in tissue culture

Cultures of melanocytes and keratocytes were exposed to 15 micrograms ml-1 tyrosinase and 4-hydroxyanisole (4-OHA) 5 X 10(-4) M to 5 X 10(-2) M for 1 to 24 h. No damage was suffered by either cell below 5 X 10(-3) M 4-OHA for 6 h, but higher concentrations and longer exposures extensively damaged both cells. Exposure of cells washed free of culture medium to tyrosinase and 4-OHA 1 X 10(-3) M for 1 h resulted also in extensive damage. This indicates that an early-formed toxic product of the reaction between tyrosinase and 4-OHA is inactivated by constituents of the medium. This was confirmed by Liquid Chromatography and Scanning Spectrophotometry which showed that a toxic 4-OHA quinone immediately reacted with nucleophilic substances in the medium resulting in products which, on accumulation, are probably responsible for the later (6 h plus) damage to melanocytes and keratocytes. A possible effect of allegedly specific melanocytotoxic drugs on keratocytes should always be borne in mind with tissue culture experiments.

Effect of azelaic acid on human malignant melanoma

In 23 patients with malignant melanoma, including some with metastases and terminal patients, topical and oral (10--15 g daily) azelaic acid given for 1--12 weeks before surgical excision of the lesions was followed by arrest and subsequent regression of the advancing edge of lesions, reduction in size and flattening of nodular areas, and progressive lightening of pigmentation. Histological and ultrastructural effects included: degeneration and disappearance of malignant epidermal and dermal melanocytes with reduction of junctional activity; epidermal proliferation and return towards normal organisation; reappearance of papillary dermis, pilosebaceous units, and sweat glands; separation of dermal melanoma tumour masses into smaller collections of cells by regenerating connective tissue; and increase in number of dermal mast cells, macrophages, and round cells. These preliminary results indicate a direct cytotoxic effect of azelaic acid on melanocytes of human melanoma.

Effect of dicarboxylic acids on lentigo maligna

Dicarboxylic acids from C8 to C14 are competitive inhibitors of tyrosinase in vitro, and here, the effect of a cream containing 15% azelaic acid (C9) on 3 cases of lentigo maligna is described. The lesions were treated for 90 days, with remarkable clinical and histological effect, maintained for up to 2 yr after cessation of treatment. Progress during treatment of one case was additionally monitored by electron microscopy, which revealed progressive elimination of abnormal melanocytes both basally and suprabasally, and their replacement by essentially normal cells engaged in normal melanogenesis. There was also progressive diminution in the general disorganization of the epidermis, and disappearance of lymphocyte response. It is concluded that dicarboxylic acids have a direct inhibitory and cytotoxic effect on abnormally active or structurally disordered melanocytes in lentigo maligna, but further investigations are required to establish their precise mode of action. Similar application of dicarboxylic acids to normal skin affects only a small proportion of melanocytes, suggesting that some phasic factor, or individual states of activity, may be concerned in their susceptibility.

Hypopigmented sarcoidosis in the negro. Report of eight cases with ultrastructural observations

The dermatological aspects of eight negro patients with hypopigmented sarcoid lesions are described. Light microscope histochemical studies in patients did not reveal the mechanism of the hypopigmentation. However, electronmicroscopy of lesions in two patients showed melanocytes undergoing changes resembling those observed in other acquired hypopigmentary conditions. It is suggested that in these disorders, melanocytes react morphologically in a similar non-specific manner, whatever the prime pathological process.

Freeze-fracture replication of organized tissue without cryoprotection

Fresh pieces of rat liver and pancreas were rapidly frozen without prior chemical fixation or cryoprotection, and replicated folloing freeze-fracture. Replicas revealed small peripheral areas free of ice crystals or damage and, within such areas, general ultrastructural morphology was essentially similar to that seen in conventionally processed material. On fracture faces of plasma and nuclear membranes a population of less prominent particles in addition to conventional membrane-associated particles was seen, and smooth areas devoid of particles of any type were seen on some nuclear membranes. These smooth areas did not appear to be similar to smooth areas allegedly arising as artifacts of conventional processing. Tight junctions and gap junctions appeared as they do in cryoprotected specimens. The results provide a base-line for assessing the possible effects of processing steps or agents on the ultrastructure of organized tissues as revealed in freeze-fracture replicas.