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Biomedical subjects

M Guarrera

Publications and source records attributed to M Guarrera.

At least 19 recordsLinked to original sources
PubMed2005

Kenogen in female androgenetic alopecia. A longitudinal study.

BACKGROUND: Kenogen indicates the physiological interval of the hair cycle in which the hair follicle remains empty after the telogen hair has been extruded and before a new anagen hair emerges. Kenogen frequency and duration are greater in men and women with androgenetic alopecia (AGA). OBJECTIVE: To study the relationship of kenogen with female AGA. METHODS: A woman with AGA, studied 14 years before, was re-examined for 2 years by the phototrichogram technique. Kenogen was identified when telogen lasted 3 months and shedding left the follicle empty. RESULTS: Kenogen lasted 1-5 months, the longest duration affecting cycles of vellus hairs, and involved more hair follicles (16 vs. 8%) than in the first observation. Cycles of vellus hairs increased in number from 4 to 13%, and cycles with a normal succession of phases decreased from 60 to 32%. CONCLUSIONS: The number of kenogen phases increased in parallel with vellus hairs and the diminished number of normal hair cycles, features that mark AGA aggravation. Kenogen seems to be related also to the progression of female AGA.

Alopecia↗
PubMed2002

Perception of baldness and hair density.

BACKGROUND: Androgenetic alopecia needs to be scored precisely. OBJECTIVE: A possible measure is the ratio between the hair density in the parietal area and that in the occipital area which, being not affected by baldness, supposedly has a 'normal' density. METHODS: On the vertex and just below the occipital protuberance of 109 men, two 1-cm(2) areas were identified. In both areas, hairs were clipped short and photographed by a videomicroscope. Hairs were then counted within a 30-mm(2)-wide central square section. RESULTS: In the occipital area, the average count was 127/cm(2), without differences among the Hamilton/Norwood classes. In the parietal area, the average density significantly diminished from 138 to 47/cm(2). A main difference was found between classes 1-3 vertex and classes 4-6. CONCLUSIONS: The parietal/occipital ratio decreased significantly only when baldness was clinically manifest. The parietal/occipital ratio cannot be a better measure of baldness severity than the rough Hamilton/Norwood scale. The perception of early baldness does not depend on the diminished hair density, but also on the progressive thinning of the hair shafts.

Adolescent↗
PubMed2001

Oxidative stress in physical urticarias.

The pathogenesis of the physical urticarias has not been completely defined. Indeed, different stimuli can induce similar clinical manifestations, some of which are capable of generating reactive oxygen species. In order to evaluate whether the generation of an oxidative stress response could be a common pathogenetic mechanism of the disease, we have determined the profile of a number of chemical and enzymatic antioxidants in blood samples from a group of patients with physical urticarias. Compared with controls, a systemic imbalance of the antioxidants was detected in the patient group with a decrease of both plasma vitamin E and cellular catalase and glutathione peroxidase activities along with an increase of superoxide dismutase activity. Moreover, an increase in the percentage of plasma polyunsaturated fatty acids, as a target for peroxidative damage, was also observed. These alterations may lead to an increased percentage of peroxidable compounds in skin and to the intracellular generation of reactive oxygen species and could therefore provide one possible explanation for the patients' urticarial response to stimuli. Even if the alteration of the antioxidant status is secondary to changes in cytokine or complement activation, our results suggest a common biochemical profile in patients with different forms of physical urticaria.

Adult↗
PubMed2001

Topical metronidazole does not abate UVB-induced erythema.

BACKGROUND: The capacity of topical metronidazole to reduce erythema severity scores in rosacea has been attributed to its anti-inflammatory activity. METHODS: Nine healthy subjects were irradiated on three 1-cm(2) areas on their volar forearm with 2 MEDs of UVB. Twenty-four hours later, one of the irradiated areas was treated daily with metronidazole 1% vanishing cream, one with the vehicle only and the third was left untreated (control). The intensity of erythema was measured, at 24, 48, 72 and 96 h after irradiation, by a Chromameter CR200 (Minolta, Japan) and expressed in the L*a*b* system. The a* parameter was taken as the measure of redness. RESULTS: Overall, redness diminished over time in a linear way, but treatments did not influence it significantly. CONCLUSION: In our vehicle, metronidazole 1% cream failed to abate the UVB-induced erythema. An activity other than the anti-inflammatory one should be suggested to explain the topical metronidazole efficacy in rosacea.

Administration, Cutaneous↗
PubMed2000

Finasteride increases anagen hair in men with androgenetic alopecia.

BACKGROUND: The growth of scalp hair is a cyclical process of successive phases of growth (anagen) and rest (telogen). In previous clinical trials in men with androgenetic alopecia, treatment with finasteride increased scalp hair counts in a defined area (i.e. increased hair density). OBJECTIVES: The current study used a phototrichogram methodology to assess the effect of finasteride on the phases of the hair growth cycle. PATIENTS/METHODS: Two hundred and twelve men, age 18-40 years, with androgenetic alopecia were randomized to receive finasteride 1 mg daily or placebo for 48 weeks. At baseline and at 24 and 48 weeks, macrophotographs were taken to measure total and anagen hair count in a 1-cm(2) target area of the scalp. RESULTS: At baseline, mean total and anagen hair counts in the finasteride group were 200 and 124 hairs, respectively (% anagen = 62%) and the anagen to telogen ratio was 1.74 (geometric mean). In the placebo group, the respective values were 196 and 119 hairs (% anagen = 60%) and 1.57. At week 48, the finasteride group had a net improvement (mean +/- SE) compared with placebo in total and anagen hair counts of 17.3 +/- 2.5 hairs (8.3% +/- 1.4%) and 27.0 +/- 2.9 hairs (26% +/- 3.1%), respectively (P < 0.001). Furthermore, treatment with finasteride resulted in a net improvement in the anagen to telogen ratio of 47% (P < 0.001). In this study, treatment with finasteride 1 mg day(-1) for 48 weeks increased both total and anagen hair counts, and improved the anagen to telogen ratio. CONCLUSIONS: These data provide direct evidence that finasteride 1 mg daily promotes the conversion of hairs into the anagen phase. These data support that finasteride treatment results in favourable effects on hair quality that contribute to the visible improvements in hair growth observed in treated patients.

Adolescent↗
PubMed1999

Assessing hair shedding in children.

BACKGROUND: The wash test is currently used to assess hair shedding, though it lacks a cut-off point of normality and any evidence of being reliable. The aim of this study is to provide data to fulfil those needs. METHODS: The wash test was employed in a standardized way on 31 children aged 3-11 years. RESULTS: The test yielded 10.68 +/- 3.91 hairs, a figure which may be considered as 'normal' for children of that age. The chi(2) test granted the validity of the method. The number of shed hairs counted in the washing basin increased with the age of the subjects. COMMENT: The wash test proved to be reliable and to be a useful tool for monitoring hair shedding. The increasing trend with age may suggest a possible prepubertal onset of androgenetic alopecia.

Age Factors↗
PubMed1998

Catalase in the stratum corneum of patients with polymorphic light eruption.

UV radiation generates reactive oxygen species, which may be involved in polymorphic light eruption. The endogenous enzymatic defense system includes catalase in the epidermis. Thirteen patients with a history of polymorphic light eruption, but free from lesions, and 13 controls were investigated from November to March. Catalase was analysed in the upper horny layer according to Colin et al.'s spectrophotometric technique. In polymorphic light eruption, catalase values were about 30% lower than in control subjects. Such deficiency was observed in patients free from the disease and not recently sun-exposed. The diminished skin catalase in irradiated polymorphic light eruption makes it possible that a longer restoration time of catalase is involved in the pathogenesis.

Adolescent↗
PubMed1998

Delayed telogen replacement in a boy's scalp.

BACKGROUND: In case the shedding telogen hair is not replaced in time by a terminal anagen hair, an empty space results. OBJECTIVE: To verify whether the phenomenon is present in prepubertal subjects. METHODS: From July 1996 to May 1997, an 8-year-old boy was submitted monthly to the phototrichogram technique. Sixty hairs were monitored throughout the study. RESULTS: 52% of all studied hairs were terminal anagen hairs throughout the study and additionally 22% were in a regular hair cycle. Vellus hairs and empty spaces were observed in 18 and 8% of follicles, respectively. In 2% of hairs, vellus hairs and empty spaces were associated. CONCLUSIONS: Vellus hairs and empty spaces are present even in children. Without gonadal androgens and expression or induction of 5alpha-reductase in the prepubertal scalp, they are unlikely to herald androgenetic alopecia (AGA) but could reflect a physiological phenomenon of 'true resting' of a small proportion of scalp hair. Androgens may increase the phenomenon which may account in part for AGA development.

Alopecia↗