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Biomedical subjects

R Marks

Publications and source records attributed to R Marks.

At least 595 records · Page 33Linked to original sources
PubMedDate not supplied

Evaluation of biomechanical properties of human skin.

Measurement of the physical properties of skin may seem "esoteric" and of little relevance to clinical science; however, the noninvasive nature of available techniques provides unique opportunities for monitoring the effects of disease, drugs, or cosmetics over time on exactly the same area of skin. In vitro testing gives repeatable standardized methods that can supply basic elastic and viscoelastic moduli for skin, which for low strain are comparable to results obtained from in vivo tests. Interpretation of in vivo tests can be difficult, as no analytical model has been developed that can relate measurements from these tests directly to basic skin properties. Each method and each implementation of that method has subtle differences from every other method so that results between studies are difficult to compare; however, the alternative to the bioengineering tests is the hand and eye, which provide subjective (and often biased), nonlinear, and notoriously variable data between individuals. Judging the severity of involvement, the changes due to treatment or progress of disease, and the efficacy of competing treatments is very difficult, even for an experienced clinician. Objective, numerical information on the effects of different active compounds and their formulations is essential if new preparations are to be optimized. Measurement of mechanical properties is one aspect of this important field of endeavor.

Biomechanical Phenomena↗
PubMedDate not supplied

EEMCO guidance for the in vivo assessment of skin greasiness. The EEMCO Group.

Sebaceous gland activity has four distinct components which are sebum production (a secretion rate function), storage (a volume function), surface output (a delivery rate function) and stratum corneum permeation (an influx rate function). The oily appearance of skin results from an excess of sebum excretion and spreading over the body surface and its interaction with the skin surface. A multi-pronged approach is often useful to assess skin greasiness with precision. The clinical evaluation of skin greasiness and its shiny appearance should be further complemented by quantifying the large pores, follicular plugs and comedones. The sebum amount present at the skin surface can be measured non-invasively using one of several methods based on solvent extraction, cigarette paper pads, photometric assessment, bentonite clay and lipid-sensitive tapes. Quantitative parameters include the sebum casual level, the sebum excretion rate, the sebum replacement time, the instant sebum delivery, the follicular excretion rate, the density in sebum-enriched reservoirs and the sustainable rate of sebum excretion. A series of environmental and biological features influence the data. Hence rigorous methodological designs are mandatory to support claims. As a rule, accuracy of the methods is adversely affected by skin temperature, degree of hydration and surface roughness. An additional confounding factor is the inherent difficulty of collecting the surface lipids without a contribution from the follicular reservoir. A better understanding of factors that alter the sebum amount at the skin surface may well assist in the development of sebosuppressive agents to help the reduction of the skin greasiness and improve acne.

Humans↗
PubMedDate not supplied

EEMCO guidance for the efficacy assessment of antiperspirants and deodorants.

Overproduction of sweat, sweaty skin and body odours are unpleasant for many social groups. Body cleansing products are designed to combat these undesirable features of skin. In addition, antiperspirant and deodorant products are more specifically used in the underarm site by a large part of the adult population. Antiperspirants are offered to control emotionally triggered sweating in the armpit. Deodorants are designed to combat malodour generated from bacteria-modified sweat. This review summarizes the physiology of eccrine, apocrine and apoeccrine sweat glands. The mechanisms of action of antiperspirants and deodorants are described as well as the factors influencing their efficacies. A series of tests using various measurement methods can be used to demonstrate the efficacy of antiperspirants. These include the gravimetric method, water evaporation quantification, electrodermal measurements, staining procedures, dye injections and cyanoacrylate skin surface strippings and casting replicas. Deodorant efficacy can be evaluated by sensory assessments performed by an expert panel. Indirect support is provided by visualization of apocrine gland excretion and collection of sweat and volatile compounds. Microbiological assessments and chromatographic analysis also provide indirect information.

Apocrine Glands↗
PubMedDate not supplied

EEMCO guidance for the assessment of hair shedding and alopecia.

Knowledge of the hair follicle anatomy and the dynamics of hair cycling is substantial. Recognizing the anagen, catagen and telogen phases as well as teloptosis and the hair eclipse phenomenon clearly characterizes the typical hair chronobiology. Physiological modulators include hormones, neuromediators, miscellaneous biomolecules, seasons, micro-inflammation and ageing. For individuals who present with the complaint of increased hair shedding or alopecia, a host of evaluation techniques are available in addition to history, physical examination and laboratory assessment. Various clinical hair techniques can help in assessing the efficacy of drugs and cosmetics on hair growth. The methods are quite similar to those used to establish a definite diagnosis in dermatological practice. Great strides have been made during the recent decades in the methodology of hair growth trials in dermatology and cosmetology. Clinical evaluations benefit from a few additional specific techniques that enhance the perception of hair (re-) growth, shedding and alopecia. These assessments include the determination of hair patterning and density that may be helped by the 'black-and-white felt' examination. Daily hair counts, the 'hair pull test' and the 'hair feathering test' are also available. Instrumental methods provide reliable quantitative information that is useful if there are adequate controls. Some photographic methods, the trichogram, hair weighing and variants of the hair growth window technique including the phototrichogram, videotrichogram and tractio-phototrichogram provide insight into the complexities of hair cycling and shedding. Skin biopsy is indicated for diagnostic purposes, especially when the hair loss is accompanied by scarring.

Alopecia↗
PubMedDate not supplied

Stress in families providing care to frail elderly relatives and the effects of receiving in-home respite services.

The present research investigated caregiver stress and strain associated with providing full-time care to a frail elderly relative. Fifty families were identified who were providing this care. Twenty-five of these families were receiving an in-home respite service. The remaining twenty-five families were on a waiting list with the same agency until such services could be provided. Extensive interviews were conducted with the identified caregiver and the elderly relative in all families. The results of this study provide a clear description of characteristics of the caregivers and their relatives on a variety of dimensions including: the conditions under which providing this care occurs, the consequences to these caregivers with respect to stress and situational strain, correlates of this stress and strain and the effects of receiving a respite service. Substantial stress was seen among all of the caregivers. Using a variety of multi-variate statistical methods several significant differences in stress and strain were seen among a variety of factors associated with the caregiving situation and between the primary caretakers receiving the respite service and those who were not. The results support the need for both formal and informal support to families in the caregiving role to aid their ability in providing this care and in inhibiting institutionalization.

Adult↗