Biocorrosion investigation of two shape memory nickel based alloys: Ni-Mn-Ga and thin film NiTi.

Thin film nitinol and single crystal Ni-Mn-Ga represent two new shape memory materials with potential to be used as percutaneously placed implant devices. However, the biocompatibility of these materials has not been adequately assessed. Immersion tests were conducted on both thin film nitinol and single crystal Ni-Mn-Ga in Hank's balanced salt solution at 37 degrees C and pH 7.4. After 12 h, large pits were found on the Ni-Mn-Ga samples while thin film nitinol displayed no signs of corrosion. Further electrochemical tests on thin film nitinol samples revealed breakdown potentials superior to a mechanically polished nitinol disc. These results suggest that passivation or electropolishing of thin film nitinol maybe unnecessary to promote corrosion resistance.

[Atypical tuberculous osteomyelitis of the humeral shaft caused by Mycobacterium avium]. / Atypische tuberculeuze osteomyelitis van de humerusschacht door Mycobacterium avium.

A 41-year-old man underwent skeletal scintigraphy due to chronic pain in the left foot and polyarthralgia. He was taking medication for gout and had previously had sarcoidosis, for which he had received corticosteroids and other therapy that was discontinued 4 years ago. Scintigraphy revealed a mass in the shaft of the left humerus that, according to biopsy, was an asymptomatic osteomyelitis caused by Mycobacterium avium. The shaft of the left humerus is an uncommon site for tuberculous osteomyelitis. A viable fistula remained after the biopsy that persisted despite pharmacologic treatment with ethambutol, rifabutin and clarithromycin. Four months later, sequestrectomy was performed with insertion of gentamicin-impregnated beads, which resulted in rapid resolution. The foot pain resolved spontaneously. The incidence of bone tuberculosis has increased over the last 2 decades. The most commonly affected sites are the spine and large joints. Infection with M. avium is sometimes involved. Because of the increasing incidence it is important to include mycobacterial infections in the differential diagnosis of focal bone lesions, especially when standard cultures are initially negative.

Comparative efficacy of clindamycin and benzoyl peroxide for in vivo suppression of Propionibacterium acnes.

BACKGROUND: Benzoyl peroxide and clindamycin are the two most widely prescribed topical antimicrobials in the treatment of acne. AIM: To compare the antimicrobial efficacy, in vivo, of benzoyl peroxide and clindamycin against Propionibacterium acnes. METHODS: Two groups of 10 subjects each, with comparable mean P. acnes baseline counts of log 5.75 to 5.85, underwent twice daily application of benzoyl peroxide or clindamycin for 14 days. RESULTS: The results of quantitatively sampling P. acnes after 3, 7 and 14 days of treatment showed that Triaz 6% benzoyl peroxide special gel produced faster and significantly greater reductions in P. acnes than did the 1% clindamycin phosphate in Cleocin-T lotion (p < 0.01). These results were paralleled by the greater reductions produced by Triaz versus Cleocin (p < 0.05) in P. acnes fluorescence. CONCLUSION: Benzoyl peroxide formulations suppress the follicular population of P. acnes more rapidly and to a greater degree than topical antibiotics such as clindamycin.

Xerosis in hypothyroidism: a potential role for the use of topical thyroid hormone in euthyroid patients.

Xerosis is an extraordinarily common problem in dermatology. Despite the knowledge of well recognized aggravating factors, its etiology is an enigma, and the management of the condition is often suboptimal. Dry skin may be a manifestation of hypothyroidism. The nature of this association is reviewed, culminating in the speculation that topical thyroid hormone may represent a useful modality in euthyroid patients with xerosis or other disorders of keratinization.

Comparative activity of benzoyl peroxide and hexachlorophene. In vivo studies against propionibacterium acnes in humans.

The bactericidal effects of benzoyl peroxide (5% lotion) and hexachlorophene (3% colloidal suspension) against Propionibacterium acnes were compared in nine healthy college students who had the microbiological and skin lipid characteristics typical of acne vulgaris, but no active lesions. Each of the two medications was applied twice daily, to opposite sides of the face, for four consecutive weeks. Hexachlorophene was effective against surface aerobes but only slightly active against P acnes. It marginally reduced free fatty acid concentrations in surface lipids and in follicular porphyrin fluorescence. Conversely, benzoyl peroxide virtually eliminated P acnes and aerobes and induced substantially decreased free fatty acid concentrations and follicular fluorescence. We conclude that benzoyl peroxide exerts its antimicrobial action in the follicles and inhibits P acnes, while the antimicrobial effectiveness of hexachlorophene is limited to the skin surface.

Percutaneous absorption, blood levels, and urinary excretion of resorcinol applied topically in humans.

The absorption and metabolic disposition of 2% resorcinol applied topically in a hydroalcoholic vehicle was determined in three human subjects. The drug penetrated the skin at a rate of 0.37 micrograms/cm2/hour. After 2 weeks of bid application of 800 mg resorcinol to about 30% of body surface of each subject, an average of 1.64% of the dosage was being excreted in 24-hour urine specimens as the glucuronide or as the sulfate conjugate. There was no resorcinol in blood drawn at weeks 1, 2, 3, and 4, or nor were there any abnormalities in thyroid function or blood chemistries at weeks 2, 3, and 4. Resorcinol (2%) appears safe for topical use in humans.

Effect of lipids on the aggregation and permeability of human stratum corneum.

The role of stratum corneum (SC) constituents in SC barrier properties was assessed directly in vitro in a reaggregated system. Fragments of SC from the sole of the foot (hyperplastic tissue) and from the calf (normal tissue) were reduced, separately, to individual cells and these cells were depleted of lipids by solvent extraction. Lipids taken from the cells themselves or from SC from other areas of the body were then added to the cells. None of the fractions used allowed for reaggregation of plantar SC cells, or of trypsinized calf SC cells. In contrast, calf SC cells reaggregated equally well with all lipids and formed coherent SC sheets. At equal lipid:cell ratios, however, plantar lipid-calf cell SC sheets were about three time more permeable to water than calf lipid-calf cell SC sheets. The effectiveness of the barrier function of the SC sheets was directly proportional to the amount of added lipid. We conclude that in normal SC the extractable lipids are intimately involved in cellular adhesion/dyshesion and in barrier formation.

A method for measuring desquamation and its use for assessing the effects of some common exfoliants.

Desquamation has been measured in the past by a counting chamber technique after corneocytes are removed from the skin surface and disaggregated in a dilute surfactant solution. However, we have found that complete corneocyte disaggregation is not always possible when these aggregates are recovered from sites where patent peeling is induced. Corneocyte counting in such instances is difficult or impossible. We have devised a method of measuring desquamation wherein the desquamating cells are determined as the total alkali-soluble protein after they are removed from the skin surface with an inert, self-hardening gel. Highly reproducible desquamation rates are obtained, characteristic of the individual subject. Using some common exfoliants, we show that pharmacologic response, observed as an increase in desquamation rate, is also an individual characteristic.

A reexamination of the potential comedogenicity of sulfur.

The present study was designed to reexamine the question of the potential comedogenicity of topical sulfur. Studies were done by two different investigators in two separate institutions with groups of 12 and 40 subjects, respectively. Biopsy specimens were obtained from the occluded test sites before and after a six-week period of treatment. Each subject received a patch test of 5% sulfur in either an octoxynol 9 (Triton X-100) or a carbomer 934P (Carbopol 934P) vehicle and one of two controls consisting of the Triton X-100 vehicle or a dry patch test. We conclude that no trend or correlation was noted between the presence or absence of sulfur in the formulation and the appearance of comedones. The Triton X-100 vehicle itself appeared to be comedogenic under the experimental conditions.

Oral zinc therapy of acne. Absorption and clinical effect.

In a double-blind controlled comparison that lasted eight weeks, tablets of zinc sulfate monohydrate, 411 mg total daily dosage, and a lactose placebo were administered orally to 22 male subjects with moderate acne. At the same time, levels of zinc were determined in serum and urine. There were no statistically significant differences in the lesion counts (papules, pustules, open comedones, and closed comedones) in the zinc-treated and lactose-treated cases, despite evidence in serum and urine of absorption of zinc. The data from this study indicate that oral zinc therapy has no early clinical effect on male patients with moderate acne.

Viscoelastic properties of intact human skin: instrumentation, hydration effects, and the contribution of the stratum corneum.

Past attempts to relate mechanical properties of the stratum corneum to its state of hydration or disease condition have been hampered by the lack of adequate in vivo methodology. With the technique described herein, viscoelastic properties of the skin surface can be measured in vivo or on excised skin in vitro. This method is sensitive enough to detect changes in the properties of the stratum corneum induced by topically applied agents or by mechanical disruption of it. The viscoelastic data suggest that the outermost layers of the stratum corneum may become dry in vivo despite their proximity to the underlying wet tissue, and that the instrument is sensitive enough to measure the changes that occur. It also appears that the in vivo behavior of the stratum corneum is similar to that of isolated stratum corneum membranes which become brittle when they are dried and supple when they are hydrated.