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Biomedical subjects

N Levine

Publications and source records attributed to N Levine.

At least 127 records · Page 7Linked to original sources
PubMed1995

Design and recruitment for retinoid skin cancer prevention (SKICAP) trials. The Southwest Skin Cancer Prevention Study Group.

The retinoid skin cancer prevention (SKICAP) trials are a set of double-blind, randomized, placebo-controlled clinical trials. The SKICAP-actinic keratoses (AK) trial tests the hypothesis that daily supplementation of retinol (25,000 IU) for 5 years reduces the incidence of skin cancers in high-risk individuals, those with a history of greater than ten clinically or pathologically diagnosed AK and, at most, one prior pathologically confirmed cutaneous squamous cell carcinoma (SCC) or basal cell carcinoma (BCC). The SKICAP-SCC/BCC (S/B) trial tests the hypothesis that daily supplementation of retinol (25,000 IU) or 13-cis-retinoic acid (5 or 10 mg) for 3 years reduces skin cancer incidence in very high-risk individuals, those with a history of at least four pathologically confirmed SCCs or BCCs. Between 1984 and 1988, 2800 participants were enrolled at two clinics on the SKICAP-AK trial; and between 1985 and 1990, a total of 719 participants were enrolled at four clinics on the SKICAP-S/B trial. The initial recruitment strategy was referral by dermatologists, but low accrual necessitated the use of other strategies to achieve enrollment goals, which included involving additional clinics and using paid trial-specific advertisements in print and electronic media. Thirteen % of the SKICAP-AK participants and 36% of the SKICAP-S/B participants were enrolled through dermatologist referral, whereas paid advertisements resulted in enrollment of 87% of SKICAP-AK and 43% of SKICAP-S/B participants. A population-based skin cancer registry was used to identify and enroll the remaining 21% of the SKICAP-S/B participants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

A thermodynamic investigation of the melting of B-Z junction forming DNA oligomers.

Ultraviolet absorbance methods were used to characterize the thermodynamics of melting of a series of 16 bp deoxyoligonucleotides over a wide range of NaCl concentrations (0-4.5 M) and to obtain complete thermodynamic profiles for their melting at 0.115 and 4.5 M NaCl. The sequence of the series (one strand of duplex) was: 5'-CGCGCGCGAMNGACTG-3', where C indicates m5dC and -MN- was varied to include all combinations of Py:Py stacks (CC, TT, CT, TC). The unmethylated deoxyoligonucleotide 5'-CGCGCGCGACTGACTG-3' was used as a control sequence. All of the methylated oligonucleotides studied undergo a NaCl-induced transition to a hybrid form containing a left-handed, Z-DNA, region joined to a right-handed region by a B-Z junction. Our experiments allowed us to quantitatively evaluate the effects of NaCl, sequence, and methylation and the transition to the hybrid BZ structure on DNA thermal stability. We found that alteration of a single dinucleotide step has profound effects on the thermal stabilities of the 16 bp fragments studied. Methylation was found to destabilize the double helix, resulting in a decrease in Tm. Transition to the hybrid BZ structure, somewhat surprisingly, was found to only slightly destabilize DNA, with an observed decrease in free energy of melting of approximately 0.5 kcal/mol relative to the control, right-handed, sequence in high salt. Transition melting temperatures (Tm) were found, in agreement with previous studies on polymeric DNA, to depend upon NaCl concentration in a complicated, nonlinear fashion. m values increase to maximal values at circa 1.0 M NaCl, but decrease thereafter with further addition of salt.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1994

Coat color darkening in a dog in response to a potent melanotropic peptide.

Analogues of a melanocyte-stimulating hormone (alpha-MSH) have been documented to be effective in inducing integumental melanogenesis in several species. These melanotropin analogues are more potent than the natural hormone and have prolonged biological activity, without apparent teratogenic or other toxic effects, at least in rodents. In a pilot study, a cyclic alpha-MSH analogue, Ac-[Nle4, Asp5, D-Phe7, Lys10] alpha-MSH4-10-NH2, was administered SC to a dog at a dose of 1 mg of analogue in 1 ml of 0.9% NaCl for 3 weeks, without noticeable adverse effects. There was gradual and extensive darkening of the coat, which originally was predominantly tan, with tips of black. Initially, the darkening involved face and extremities, then gradually expanded to include the trunk and tail hair. Visual pigmentation peaked approximately 2 months after injections were completed. As new hair growth continued subsequent to the injections, the original tan color appeared at the proximal end of the hair shaft, leaving a dark terminal band on all affected hairs. These observations clearly indicated that follicular melanogenesis can be induced in dogs by treatment with a melanotropic peptide.

Animals↗
PubMed1994

Dermatologic aspects of sports medicine.

The skin is the barrier between the athlete and the sports milieu and is subjected to many insults. The purpose of this article is to review traumatic injuries to the cutaneous infections, environmental injuries, and exacerbation of preexisting dermatoses, which occur in sports enthusiasts. Emphasis will be placed on prevention and early therapeutic intervention.

Athletic Injuries↗
PubMed1994

A comparison of the efficacy of topical tretinoin and low-dose oral isotretinoin in rosacea.

BACKGROUND AND DESIGN: Twenty-two patients with severe or recalcitrant rosacea were divided into three treatment groups in a randomized, double-blind trial that compared low-dose oral isotretinoin (10 mg/d), topically applied tretinoin (0.025% cream), and the combined use of both isotretinoin and tretinoin. For the first 16 weeks of the trial, subjects received one of these three trial regimens. For the final 16 weeks, isotretinoin was withheld while tretinoin cream or a placebo cream was continued. RESULTS: Twenty subjects completed the trial. Each treatment produced therapeutic benefits with regard to the number of papules and pustules and erythema. Treatment with oral isotretinoin appeared to give a more rapid onset of improvement, but there were no differences between the groups after 16 weeks. This level of improvement continued during the succeeding 16 weeks of observation whether the subjects used the tretinoin or the placebo cream. Adverse events were minimal and well tolerated in all groups. CONCLUSIONS: Low-dose oral isotretinoin and topical tretinoin cream therapy appear to be beneficial in the treatment of severe or recalcitrant rosacea. No additive benefit is noted with the combined use of these two modalities.

Administration, Oral↗
PubMed1994

Mohs' micrographic surgery and prompt reconstruction for basal cell carcinoma: report of 62 cases using the combined method.

Aggressive, recurrent, and difficult to manage skin cancers may require complex solutions. In this review of 62 skin cancers, we demonstrate a novel approach to the management of these tumors. Mohs' micrographic surgery was used to remove the tumor, and was followed by immediate or delayed plastic surgical repair. Using this combined method, the highest attainable cure rate is linked with a coordinated prompt cosmetic repair. In this series of 54 patients with 62 skin cancers, there was one recurrence with a follow-up of one to four years. Most cases (65%) involved reconstruction within ten days of tumor removal. Eighty-one percent had a single-stage reconstruction. In seventeen patients, new tumors developed at other sites during the four-year follow-up period. On the basis of our experience with this combined method, we feel that Mohs' surgery, coordinated with prompt plastic repair, offers distinct advantages in the management of difficult skin cancers.

Adult↗
PubMed1993

Relationship among physicochemical properties, skin permeability, and topical activity of the racemic compound and pure enantiomers of a new antifungal.

The topical antifungal Sch-39304 is a racemic compound comprised of two enantiomers, Sch-42427 and Sch-42426, only one of which (Sch-42427) is pharmacologically active. The pure enantiomers have a lower melting point and, therefore, a higher solubility than the racemic compound. Because of these differences in physicochemical properties, the concentration of the pure enantiomers in vehicles and in the skin was predicted to be an order of magnitude higher than the racemic compound. It was hoped that the pharmacological activity would also be higher. By measuring the flux of the chiral forms through human cadaver skin, the expected differences in skin solubility were confirmed. However, only a minimal difference between racemate and active enantiomer was observed in the lesion scores using a guinea pig dermatophyte model. By fitting the data to the Emax pharmacodynamic model, it is demonstrated that the maximum effect occurs at a concentration lower than the saturated concentration of the less soluble racemic compound. The data illustrate that the efficacy of topically active compounds may not be linearly related to drug concentration in either the vehicle or the skin.

Adult↗
PubMed1993

Down's syndrome and Alzheimer's disease.

Individuals with Down's syndrome (DS) who live to be 40 years of age will demonstrate neuropathological changes that are consistent with Alzheimer's disease (AD). Due to modern medical intervention, we are now observing an aging DS population. Middle-aged Down's syndrome adults are actually considered to be "very old," and it is not uncommon to observe a progressive loss of cognitive function and a decline in the ability to perform daily tasks consistent with that seen in Alzheimer's disease. At this stage, the DS individual will not be able to perform daily preventive dental care and may be unable to cooperate for professional dental care. Clinicians who care for DS adults must be aware of this problem when preparing their dental treatment plans, which must emphasize preventive care prior to the onset of dementia and the maintenance of that program during their patients' cognitive decline. In the latter stages of AD, it may be necessary to extract all the remaining teeth due to the inability of the individual or care giver to provide adequate oral hygiene to prevent dental caries or periodontal disease.

Adult↗