Nicotinamide–adenine dinucleotide-specific isocitrate dehydrogenase from pea mitochondria: Purification and Properties

1. A method of stabilizing the enzyme by using glycerol is described. 2. A purification procedure is presented giving a higher purification than previously described. 3. Data showing substrate activation and activation by citrate are presented. 4. Kinetic constants for NAD(+), NADH and certain bivalent metal ions are given. 5. Pronounced inhibitory buffer effects are described. 6. A brief comparison between the NAD-specific isocitrate dehydrogenase from peas and that from other sources is made.     

Using clinicopathological analysis of general practitioner skin surgery to determine educational requirements and guidelines.

OBJECTIVE--To study the impact of skin surgery in general practice on the workload of a pathology laboratory and to identify what further training might be helpful. DESIGN--Analysis of skin biopsy specimens from general practitioners before and after their new contract to determine numbers of specimens, changes in diagnoses, adequacy of treatment of malignant tumours, and areas of low diagnostic accuracy. SETTING--District general hospital. SUBJECTS--All 1017 skin biopsy specimens from general practice for 15 months before and 12 months after the new general practitioner contract. RESULTS--The number of pathology specimens received increased from 16 to 65 per month (median = 6 submitted by each general practitioner in the post-contract year). The proportion of the more common pathological diagnoses was unchanged between the two periods, but the proportion of correctly diagnosed naevi, cysts, and seborrhoeic keratoses increased in the second. Although few diagnoses were overtly incorrect, accurate diagnosis of dermatofibromas and malignancies decreased after the contract, and the overall correct diagnosis rate for seborrhoeic keratoses, dermatofibromas, rashes, and malignancies was below 30%. Only nine out of 21 squamous cell carcinomas were adequately excised with tumour free margins, and follow up of malignant tumours may have been inadequate. CONCLUSIONS--Skin surgery in general practice has advantages but matters of concern are the increase in laboratory workload, the excision of some benign lesions, and the inappropriateness of biopsy of rashes. Squamous cell carcinoma and other malignant tumours submitted for pathological examination were often unsuspected and inadequately excised, and heightened suspicion is recommended. Pathology request forms may need redesigning to encourage provision of clinical details.     

Effect of Phosphate and Other Anions on Trimethylarsine Formation by Candida humicola

Phosphate inhibited the formation of trimethylarsine from arsenite, arsenate, and monomethylarsonate, but not from dimethylarsinate, by growing cultures of Candida humicola. Phosphite suppressed trimethylarsine production by growing cultures from monomethylarsonate but not from arsenate and dimethylarsinate, and hypophosphite caused a temporary inhibition of both proliferation and the conversion of these three arsenic sources to trimethylarsine. Resting cells of C. humicola derived from cultures grown in arsenic-free media generated the volatile arsenical only after a lag phase. High antimonate concentrations reduced the rate of conversion of arsenate to trimethylarsine by resting cells, but nitrate was without effect.     

Factors affecting trimethylarsine and dimethylselenide formation byCandida humicola

Selenite, selenate, and tellurate inhibited the conversion of arsenate to trimethylarsine byCandida humicola. Trimethylarsine disappeared from the gas phase when incubated withC. humicola in the presence of selenium or tellurium salts. The fungus generated dimethyl-selenide from selenite and selenate and an unidentified gas from tellurate. Sulfate but not arsenate, tellurate, or phosphate inhibited the conversion of selenate to dimethylselenide. Arsenate-grown cells generated trimethylarsine from arsenate, and selenate-grown cells formed dimethylselenide from selenate with almost no lag phase. Cells grown in media with selenate or with no additions only formed the alkylarsine from arsenate after a lag phase, and those grown in solutions with arsenate or no additions produced dimethylselenide slowly from selenate.     

Pigmented Nevi—Induced Changes in the Junctional Component

The pigmented nevus represents a potentially more dynamic lesion than has been indicated by most published studies. New nevus cell clusters frequently appear in the epidermis over the residual portion of a nevus that remains after partial surgical excision. Even in relatively inactive nevi in adults, new junctional nevus cells may be induced by surgical trauma. This stimulated growth usually regresses by the time one year or more has elapsed. The growth of nevus cells is probably comparable to that induced in other cells by traumatic injury. There is no evidence to suggest that it is related to the development of melanoma in pigmented nevi.     

In vitro human keratinocyte migration rates are associated with SNPs in the KRT1 interval

Efforts to develop effective therapeutic treatments for promoting fast wound healing after injury to the epidermis are hindered by a lack of understanding of the factors involved. Re-epithelialization is an essential step of wound healing involving the migration of epidermal keratinocytes over the wound site. Here, we examine genetic variants in the keratin-1 (KRT1) locus for association with migration rates of human epidermal keratinocytes (HEK) isolated from different individuals. Although the role of intermediate filament genes, including KRT1, in wound activated keratinocytes is well established, this is the first study to examine if genetic variants in humans contribute to differences in the migration rates of these cells. Using an in vitro scratch wound assay we observe quantifiable variation in HEK migration rates in two independent sets of samples; 24 samples in the first set and 17 samples in the second set. We analyze genetic variants in the KRT1 interval and identify SNPs significantly associated with HEK migration rates in both samples sets. Additionally, we show in the first set of samples that the average migration rate of HEK cells homozygous for one common haplotype pattern in the KRT1 interval is significantly faster than that of HEK cells homozygous for a second common haplotype pattern. Our study demonstrates that genetic variants in the KRT1 interval contribute to quantifiable differences in the migration rates of keratinocytes isolated from different individuals. Furthermore we show that in vitro cell assays can successfully be used to deconstruct complex traits into simple biological model systems for genetic association studies.