Treatment of invasive squamous cell carcinoma with 5-percent imiquimod cream.

Skin cancer is a major problem in the elderly. Squamous cell carcinoma (SCC), the second most common skin cancer, typically occurs in this age group. Despite a number of modalities readily available for treatment (depending on the tumor site, and depth of invasion) there remains the problem of individuals with multiple lesions who may be unsuitable for existing treatments for SCC, particularly surgery. Consequently, the search for novel treatments continues. To our knowledge, there are only 6 published reports of invasive SCC treated with 5-percent imiquimod cream.

Signal transduction in natural killer cells.

Tolerance of natural killer (NK) cells toward normal cells is mediated through their expression of inhibitory receptors that detect the normal expression of self in the form of class I major histocompatibility complex (MHC-I) molecules on target cells. These MHC-I-binding inhibitory receptors recruit tyrosine phosphatases, which are believed to counteract activating receptor-stimulated tyrosine kinases. The perpetual balance between signals derived from inhibitory and activating receptors controls NK cell responsiveness and provides an interesting paradigm of signaling cross talk. This review summarizes our knowledge of the intracellular mechanisms by which cell surface receptors influence biological responses by NK cells. Special emphasis focuses on the dynamic signaling events at the NK immune synapse and the unique signaling characteristics of specific receptors, such as NKG2D, 2B4, and KIR2DL4.

Papulosquamous dermatitis. Syphilis: a forgotten disease?

We report a case of secondary syphilis in a 54-year-old, bisexual, HIV positive man. Although syphilis is a well-known sexually-transmitted infection, it is not widely seen nowadays. However, a possible diagnosis of syphilis should not be overlooked in any individual, irrespective of HIV status.

Pyodermatitis-pyostomatitis vegetans complicated by methicillin-resistant Staphylococcus aureus infection.

Pyodermatitis-pyostomatitis vegetans (PPV), a rare disorder of the skin and oral mucosa, is considered a highly specific marker for inflammatory bowel disease, especially ulcerative colitis (UC). Oral lesions (pyostomatitis vegetans) are seen without skin involvement but rarely without gastrointestinal symptoms. Bowel symptoms may be minimal and precede the onset of other lesions by months or years. Dermatologically, PPV is characterized by annular, pustular lesions, which may precede or appear at the same time as the oral lesions. We report a case of PPV and UC in which presentation was confused by acneiform lesions and methicillin-resistant Staphylococcus aureus colonization. Management was complicated because of the patient's job commitments and need to travel, and the involvement of a number of different specialties at different locations.

Evidence of powerful substrate electric fields in DNA photolyase: implications for thymidine dimer repair.

DNA photolyase is a flavoprotein that repairs cyclobutylpyrimidine dimers by ultrafast photoinduced electron transfer. One unusual feature of this enzyme is the configuration of the FAD cofactor, where the isoalloxazine and adenine rings are nearly in vdW contact. We have measured the steady-state and transient absorption spectra and excited-state decay kinetics of oxidized (FAD-containing, folate-depleted) Escherichia coli DNA photolyase with and without dinucleotide and polynucleotide single-stranded thymidine dimer substrates. The steady-state absorption spectrum for the enzyme-polynucleotide substrate complex showed a blue shift, as seen previously by Jorns et al. (1). No shift was observed for the dinucleotide substrate, suggesting that there are significant differences in the binding geometry of dinucleotide versus polynucleotide dimer lesions. Evidence was obtained from transient absorption experiments for a long-lived charge-transfer complex involving the isoalloxazine of the FAD cofactor. No evidence of excited-state quenching was measurable upon binding either substrate. To explain these data, we hypothesize the existence of a large substrate electric field in the cavity containing the FAD cofactor. A calculation of the magnitude and direction of this dipolar electric field is consistent with electrochromic band shifts for both S(0) --> S(1) and S(0) --> S(2) transitions. These observations suggest that the substrate dipolar electric field may be a critical component in its electron-transfer-mediated repair by photolyase and that the unique relative orientation of the isoalloxazine and adenine rings may have resulted from the consequences of the dipolar substrate field.

Cutaneous lesions in a case of acute megakaryoblastic leukaemia.

We describe the case of a 68-year-old woman who presented with asymptomatic skin nodules and symptoms of anaemia, and was found to have acute megakaryoblastic leukaemia with fibrosis, a condition now believed to correspond to the former diagnosis of acute myelofibrosis. There is only one previous report of skin lesions developing in this condition.

REE chemistry and Sm-Nd systematics of late Archean weathering profiles in the Fortescue Group, Western Australia.

Two weathering profiles, each consisting of an upper, sericite-rich zone and a lower, chlorite-rich zone, are preserved between flows of the Mt. Roe Basalt in the Fortescue Group, Hamersley Basin, Western Australia. REE concentrations in samples from these two profiles, which originally developed ca 2,760 Ma, show large variations depending on stratigraphic position. LREE abundances and (La/Yb)N are greatest at depths of 3-6 m below the paleosurface of the Mt. Roe #1 profile and are somewhat lower in samples above this level. The LREEs reach concentrations 6-9 times greater than in the underlying basalt, and thus appear to have been mobilized downward in the paleosol and concentrated in its middle part. LREE concentrations in the #2 profile show a similar distribution but with a sharp increase in all REE concentrations within 50 cm of the paleosurface. The distinction between the REE profiles in the two paleosols may be related to the difference in the overlying material. The #1 paleosol is overlain by a few meters of sediments and then by basalt, whereas the #2 paleosol is directly overlain by basalt. The LREEs appear to have been mobilized both during chemical weathering of the parental basalt and during later lower-greenschist-facies metamorphism and metasomatism of the paleosols. Remobilization of the REEs during the regional metamorphism of the Fortescue Group is confirmed by a whole-rock Sm-Nd reference isochron of Mt. Roe #1 samples with an age of 2,151 +/- 360 Ma. Variable initial 143Nd/144Nd values of unweathered basalt samples which may represent the paleosol protolith prevents a confident determination of the magnitude of LREE mobility. Both the initial mobilization of the REEs during weathering and the metasomatic remobilization appear to have taken place under redox conditions where Ce was present dominantly as Ce3+, because Ce anomalies are not developed within the sericite zone samples regardless of concentration. Europium anomalies in the paleoweathering profile are somewhat variable and were probably modified by mobilization of Eu2+ at metamorphic conditions. In all samples, the HREEs appear to have been relatively immobile and correlate with Al, Ti, Cr, V, Zr, and Nb. Sm-Nd systematics and REE patterns of four unweathered basalt samples indicate derivation of the Mt. Roe Basalts from a heterogeneous and enriched source having epsilon Nd between -4.0 and -7.4. Initial 143Nd/144Nd values of these basalts are even lower than those reported by NELSON et al. (1992) for Fortescue Group basalts and indicate a substantial crustal component in the generation of Mt. Roe Basalts.

A histopathological study of 643 cutaneous horns.

A retrospective study of 643 cutaneous horns examined in our department between 1970 and 1989 revealed that 38.9% were derived from malignant or premalignant epidermal lesions, and 61.1% from benign lesions. Four main features were associated with premalignant or malignant histopathological change at the base of a cutaneous horn (base pathology). These were: (i) age--the mean age of the patients whose cutaneous horns showed premalignant or malignant base pathology was 8.9 years greater than the mean age of the patients where base pathology was benign (P less than 0.0005); (ii) sex--males were more likely to develop a cutaneous horn with (pre)malignant base pathology (P less than 0.001); (iii) site--over 70% of all (pre)malignant lesions were found on the nose, pinnae, backs of hands, scalp, forearms and the face; a cutaneous horn found at these sites was 2.1 times more likely to have derived from a (pre)malignant base than from any other part of the body (P less than 0.0001); (iv) geometry of the lesion--lesions with a wide base or a low height-to-base ratio were significantly more likely to show (pre)malignant base pathology. Of those solar keratoses giving rise to cutaneous horns, 8.9% also showed histological evidence of change to squamous cell carcinoma (SCC); this figure was not significantly different from the 6.2% of solar keratoses without horns that showed SCC change during the same period (1970-89).

Is erythrokeratoderma one disorder? A clinical and ultrastructural study of two siblings.

Two sisters with erythrokeratoderma are described. In the younger sister the clinical appearance corresponded to erythrokeratoderma variabilis (EKV), whereas in the older sister it corresponded to progressive symmetrical erythrokeratoderma (PSEK). Ultrastructural findings in both cases were identical. We suggest that EKV and PSEK are different manifestations of a single condition.

The timing of alkali metasomatism in paleosols.

We have measured the concentrations of rubidium and strontium and 87Sr/86Sr values of whole-rock samples from three paleosols of different ages. The oldest of the three weathering horizons, the 2,760 Ma Mt. Roe #1 paleosol in the Fortescue Group of Western Australia, experienced addition of Rb, and probably Sr, at 2,168 +/- 10 Ma. The intermediate paleosol, developed on the Hekpoort Basalt in South Africa, is estimated to have formed at 2,200 Ma, and yields a Rb-Sr isochron age of 1,925 +/- 32 Ma. The youngest of the three paleosols, developed on the Ongeluk basalt in Griqualand West, South Africa ca. 1,900 Ma, yielded a Rb-Sr age of 1,257 +/- 11 Ma. The Rb-Sr systematics of all three paleosols were reset during post-weathering metasomatism related to local or regional thermal disturbances. The Rb-Sr systematics of the paleosols were not subsequently disturbed. The near-complete removal of the alkali and alkaline earth elements from these paleosols during weathering made them particularly susceptible to resetting of their Rb-Sr systematics. Paleosols of this type are therefore sensitive indicators of the timing of thermal disturbances.

Trauma-induced bullous pemphigoid.

We describe three patients with bullous pemphigoid who presented with bullae at sites of trauma and with little spread of the condition outside such areas. The diagnosis was confirmed by histology and direct and/or indirect immunofluorescence; electron microscopy was performed in two cases to rule out the diagnosis of epidermolysis bullosa acquisita (EBA). Treatment was with either systemic steroids or ACTH in all three cases. Trauma-induced bullous pemphigoid should be included in the differential diagnosis of localized blistering eruptions.

Delayed patch test reactions at days 7 and 9.

403 consecutive patients were examined on days 2, 4, 7, and 9 following application of patch tests. Late positive reactions, i.e., those which manifested after day 4, were seen in 29 patients (7.2%). The allergens which most commonly produced late positive reactions were neomycin (7), potassium dichromate (4), and cobalt (3). Paired patch test readings on days 4 and 7 were more reliable than those on days 2 and 4. If only 1 patch test reading were performed, a single reading on day 4 would have been most useful. The reading on day 9 proved to be of limited value. Of 11 patients who were retested after an interval of more than 6 months, 7 showed earlier eliciting reactions, which may have been due to active sensitization.

A case of actinic lichen planus.

The condition known as actinic lichen planus is believed to be a particular variant of lichen planus which occurs on light-exposed areas. Synonyms include lichen planus tropicus, lichen planus subtropicus, lichen planus in subtropical countries, lichenoid melanodermatitis, and lichen planus atrophicus annularis. The majority of reported cases are from the Middle East, although there have also been cases in North Africans, black South Africans, Kenyans, and Indians. There are other reports from Italy, the United States, and the Netherlands. 'Summertime actinic lichenoid eruption' has been suggested as a better term for the condition. A case of actinic lichen planus is described in a boy who has been resident in the United Kingdom all his life, but who is of Egyptian extraction.