An appraisal of laboratory models of androgenetic alopecia: A systematic review.

Background: Androgenetic alopecia (AGA) is the most common form of non-scarring alopecia in humans. Several studies have used different laboratory models to study the pathogenesis and interventions for AGA. These study models have proved beneficial and have led to the approval of two drugs. However, the need to build on existing knowledge remains by examining the relevance of study models to the disease. Objective: We sought to appraise laboratory or pre-clinical models of AGA. Method: We searched through databases (PubMed, ScienceDirect, Web of Science, World CAT, Scopus and Google Scholar) for articles on AGA-related studies from 1942 to March 2019 with a focus on study models. Results: The search rendered 101 studies after screening and deduplication. Several studies (70) used in vitro models, mostly consisting of two-dimensional monolayer cells for experiments involving the characterization of androgen and 5-alpha reductase (5AR) and inhibition thereof, the effects of dihydrotestosterone (DHT) and biomarker(s) of AGA. Twenty-seven studies used in vivo models of mice and monkeys to investigate DHT synthesis, the expression and inhibition of 5AR and hair growth. Only four studies used AGA-related or healthy excisional/punch biopsy explants as ex vivo models to study the action of 5AR inhibitors and AGA-associated genes. No study used three-dimensional [3-D] organoids or organotypic human skin culture models. Conclusion: We recommend clinically relevant laboratory models like human or patient-derived 3-D organoids or organotypic skin in AGA-related studies. These models are closer to human scalp tissue and minimize the use of laboratory animals and could ultimately facilitate novel therapeutics.

Nanomedicine: action of metal nanoparticles on neuronal nitric oxide synthase-fluorimetric analysis on the mechanism for fibrillogenesis.

The incubation of neuronal nitric oxide synthase with the five amyloid peptide fragments [Aß17-21; Aß25-29; Aß29-33; Aß33-37; Aß25-37] catalyzed the formation of fibrils. The role of neuronal isomer (nNOS) involved the entrapment of free monomers and seed aggregates to initiate the events of nucleation and elongation, critical for the formation of fibrils. It was evident that the hydrophobic nature of Aß17-21, the three glycine zipper peptides [Aß25-29; Aß29-33; Aß33-37] and Aß25-37 was a trigger in the formation of fibrils and was a force critical in the association of the peptides with the enzyme. Gold and silver nanoparticles (average 4.0 nm) inhibited fibril formation when added to the induced fibrils from nNOS-Aß incubation. The addition of nNOS and/or Aß to co-incubated solutions of nanoparticle-Aß or nanoparticle-nNOS respectively did not prevent fibril formation but reversed it. Three mechanisms for this reversal were proposed: (1) depletion of free Aß monomer in solution and blocking potential aggregation sites on the nNOS molecule due to large surface area of the nanoparticle (2) hydrophobic interaction between the Aß peptide and nanoparticle (3) disruption of binary adducts between Aß-peptides and nNOS by nanoparticles.

Colon and rectal cancer in Ibadan, Nigeria: an update.

INTRODUCTION: Colorectal cancer was hitherto a rarity in the rural African in general and in Nigerians inclusive. Ibadan is a sprawling city in Western Nigeria with a population of about 2.5 million inhabitants. Lately, several publications from surgeons in this city have alluded to an increase in the number of colorectal cancer cases managed in the teaching hospital. OBJECTIVES: To examine the incidence of this disease over 10 years in order to confirm or exclude the apparent significant increase in colorectal cancer cases in Ibadan, Nigeria. METHOD: This is a retrospective study highlighting the age, sex, clinical features, operations performed and histopathological subtypes of patients who had surgery for colorectal cancer in the University College Hospital Ibadan between July 1995 and August 2004. RESULTS: Two and sixty-eight patients were seen over 10 years. The male:female ratio was 1.16:1. The mean age was 41 years and the peak age was the 51- to 60-years group. Fourteen per cent of the patients were 30 years and below. Sixty-two per cent of the patients had rectal carcinoma while 33.2% had colonic carcinoma. Around 60.7% of colonic lesions were right-sided. The most common histopathological subtype was adenocarcinoma (78.8%), mucinous adenocarcinoma was 10.8% and signet ring type was 2.6%. CONCLUSION: Colorectal cancer is a disease on the increase in Ibadan. The mean age of 41 years is much lower than in the Western world. The male:female ratio still favours male patients slightly. About one in seven patients are 30 years and below. Adenomatous polyps were absent in the resected specimens.