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Biomedical subjects

R Ramsden

Publications and source records attributed to R Ramsden.

26 records · Page 2Linked to original sources
PubMed1993

Type 2 neurofibromatosis: the need for supraregional care?

The results of a U.K. study of 145 cases of type 2 neurofibromatosis has shown generally very poor operative results in terms of hearing and facial nerve preservation. Only 9 out of 118 vestibular schwannoma (acoustic neuroma) operations resulted in any clinically detectable hearing preservation and only 32 left the patient with good or normal (House grade I or II) ipsilateral facial nerve function. Although operation is still the definitive treatment of vestibular schwannoma (acoustic neuroma) and may be a lifesaving procedure, it appears that the evidence in favour of early operation is only valid when carried out in highly specialized centres. The special problems of NF2 cases who may go on to develop multiple spinal and cranial tumours making them wheelchair bound and blind as well as deaf warrants a careful experienced approach. Timing of operations may be critical for the enhancement of useful years of quality life. We therefore propose the setting up of a national NF2 register, with the management of cases at a few supraregional centres.

Adult↗
PubMed1992

A genetic study of type 2 neurofibromatosis in the United Kingdom. I. Prevalence, mutation rate, fitness, and confirmation of maternal transmission effect on severity.

A clinical and genetic study of type 2 neurofibromatosis (NF2) has been carried out in the United Kingdom. Virtually complete ascertainment of cases in the north-west of England was achieved and suggests a population incidence of 1 in 33,000 to 40,000. In the UK as a whole, 150 cases have been identified and been used to study the clinical and genetic features of NF2. The autosomal dominant inheritance of NF2 was confirmed, 49% of cases were assessed as representing new mutations, and the mutation rate was estimated to be 6.5 x 10(-6). Evidence to support a maternal gene effect was found in that age at onset was 18.17 years in 36 maternally inherited cases and 24.5 in 20 paternally inherited cases (p = 0.027). The preponderance of maternally inherited cases was also significant (p = 0.03). Data are presented which suggest that there are two types of NF2, one with later onset and bilateral vestibular schwannomas as the only usual feature, and the other with earlier onset and multiple other tumours. A considerable number of cases did not fall easily into one or other group and other factors such as maternal effect on severity and anticipation need to be considered.

Adolescent↗
PubMed1992

Null phenotype for cytochrome P450 2B2 in the rat results from a deletion of its structural gene.

The absence of phenobarbital (PB)-inducible cytochrome P450 2B2 (CYP2B2) in hepatic microsomes from Marshall 520 (M520) and Wistar Munich (WM) inbred strains of rat was previously reported [Biochem. Genet. 25:527-534 (1987)], and it was subsequently shown for M520 rats that corresponding CYP2B2 mRNA was not detected in hepatic extracts from either control or PB-treated animals [DNA 8:29-37 (1989)]. In the present study, solution hybridization was used to quantify PB-induced CYP2B2 and CYP2B1 mRNAs in livers from M520, WM, and outbred Sprague-Dawley rats, as well as additional inbred strains that express all known electrophoretic phenotypes for both of these closely related isozymes. Amounts of these mRNAs were also measured for F1 and F2 progenies of crosses involving M520 rats. The results indicated that the extent of PB induction of both isozymes appears to be independent of the electrophoretic phenotype. It was also shown that the null phenotype for CYP2B2 observed in M520 rats results from a mutation of a single autosomal gene and is inherited codominantly, regarding protein and mRNA phenotypes. Analyses of restriction digests and specific polymerase chain reaction products of hepatic DNAs revealed that the basis for the null phenotype of CYP2B2 in M520 and WM rats was a deletion of the CYP2B2 gene.

Alleles↗
PubMed1992

Netilmycin and vancomycin in the treatment of peritonitis in CAPD patients.

This study was undertaken to evaluate: 1. The efficacy of netilmycin and vancomycin as combined first line antimicrobial regime, compared to cefuroxime, in the treatment of peritonitis. 2. To measure the levels of netilmycin and vancomycin in the serum and dialysate. 3. To report on the use of this combination over a one year period and compare it with that of cefuroxime used during the previous one year.

Adult↗
PubMed1975

Hepatitis in skunks caused by the virus of infectious canine hepatitis.

Two cases of acute, fatal, hepatitis occurred in young, striped skunks (Mephitis mephitis) trapped in southern Ontario. Histologically, lesions in the liver were similar to infectious canine hepatitis. A virus was isolated which produced large intranuclear inclusions in dog kidney cell cultures. These inclusions were Feulgen-positive and fluoresced green with acridine orange stain. The skunk hepatitis isolate was identified as the virus of infectious canine hepatitis by virus neutralization tests.

Adenoviruses, Canine↗
PubMedDate not supplied

Evaluation of performance with the COMBI40 cochlear implant in adults: a multicentric clinical study.

The present multicentric clinical study involves 19 centres, 16 of them in German-speaking countries, 1 British, 1 Polish and 1 Hungarian. 60 postlingually deafened adults with a mean age of 47.5 years (20-70) and mean duration of deafness of 5.3 years (0.5-20) have been evaluated with the MED-EL COMBI 40 cochlear implant which implements a high-rate continuous-interleaved-sampling strategy with 8 channels. Safety and effectiveness data have been collected. Speech perception tests include a 16-consonant, an 8-vowel, a sentence and a monosyllabic-word test in all languages and a 2-digit figure test in all languages but English. Test intervals are 1, 3, 6 months and 1 year after first fitting. 41 of the 60 postlingually deafened adult study patients have completed their 6-month evaluation. While their pre-operative monosyllabic-word score was 0%, their mean monosyllabic-word score 6 months after first fitting was 48% (8-90) with a median of 50%. The mean sentence understanding was 84% (24-100) with a median of 90%. The respective values for the 1-year evaluations with 25 patients are a mean of 50% (5-85), with a median of 60% for the monosyllables and a mean of 89% (30-100), with a median of 97%, for the sentences.

Adult↗