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Biomedical subjects

R C Wallace

Publications and source records attributed to R C Wallace.

29 records · Page 2Linked to original sources

Alpha thalassaemia: a potential source of error in DNA linkage studies for adult polycystic kidney disease.

DNA polymorphisms associated with adult polycystic kidney disease and detected by restriction enzymes PvuII and RsaI were sought in 18 members of a Greek Cypriot family. The adult polycystic kidney disease (APKD) defect was shown to segregate with a specific 3'HVR PvuII DNA polymorphism and enabled exclusion of APKD in two children incorrectly diagnosed by ultrasound. An unusual problem of the DNA linkage approach in detection of APKD is illustrated. This occurred after coinheritance of alpha+ thalassaemia and APKD, which resulted in an altered band size for the (+) RsaI restriction fragment length polymorphism.

Adolescent↗

A method for the determination of 5-phosphoribosyl 1-pyrophosphate concentrations in erythrocytes using high-performance liquid chromatography.

A method for the measurement of erythrocyte 5-phosphoribosyl 1-pyrophosphate (PP-ribose-P) using HPLC is described. Inosinic acid formed from the enzyme-catalyzed reaction of hypoxanthine and PP-ribose-P using partially purified hypoxanthine-guanine phosphoribosyltransferase is measured after chromatography on an ion-exchange column (Partisil 10 SAX). The average recovery of PP-ribose-P added to erythrocytes was 96.6%. Normal values found were 1.3 +/- 0.6 nmol PP-ribose-P/ml packed RBC (20 individuals). Replication experiments gave a coefficient of variation of 4.4%. Elevated levels in the range 4.4-7.9 nmol PP-ribose-P/ml packed RBC were found in four patients with gout and partial deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase.

Chromatography, High Pressure Liquid↗

Hypoxanthine-guanine phosphoribosyl transferase: assay using high performance liquid chromatography.

A method is described for the estimation of hypoxanthine-guanine phosphoribosyltransferase using high performance liquid chromatography. The inosine monophosphate (IMP) generated from hypoxanthine is determined, after separation on a C18 reversed phase silica column with a buffer-methanol gradient, by the absorbance at 254 nm. Simultaneous reciprocal measurement of hypoxanthine consumption is made. The assay is suitable for screening red cell lysates for hypoxanthine-guanine phosphoribosyltransferase deficiency; the results being expressed as nmol inosine monophosphate . h-1. mg-1 haemoglobin. The normal range found was 94 +/- 15 nmol IMP . h-1 . mg-1 haemoglobin and hypoxanthine-guanine phosphoribosyltransferase activities down to 1% of normal can be assayed accurately.

Chromatography, High Pressure Liquid↗

Detachable balloon embolization: concomitant use of a second safety balloon.

We describe a relatively unusual case of carotid cavernous fistula in association with a persistent trigeminal artery, presumably related to aneurysm rupture near the carotid origin of the vessel. We emphasize the use of a second, nondetachable balloon solely for the purpose of stabilizing placement of the first device at the time of detachment.

Adult↗

Intradural primary chondroblastic osteosarcoma: case report.

We report a rare case of intradural primary osteosarcoma (IPOS) in a 74-year-old man with aphasia and right-sided hemiparesis. Radiologic workup revealed a large, partially calcified, left-sided frontotemporal intracranial mass lesion. At surgery, the tumor was found to be entirely intradural; it involved the brain and subarachnoid space of the left sylvian fissure. The adjacent dura was uninvolved. Neuropathologic findings confirmed the diagnosis of chondroblastic osteosarcoma. To our knowledge, this is the sixth reported case of IPOS and the first reported case of the chondroblastic subtype.

Aged↗

Imaging and clinical characteristics of temporal bone meningioma.

BACKGROUND AND PURPOSE: Imaging characteristics of temporal bone meningioma have not been previously reported in the literature. CT and MR imaging findings in 13 cases of temporal bone meningioma are reviewed to define specific imaging features. METHODS: A retrospective review of our institutional case archive revealed 13 cases of histologically confirmed temporal bone meningioma. CT and MR imaging studies were reviewed to characterize mass location, vector of spread, bone changes, enhancement characteristics, and intracranial patterns of involvement. Clinical presenting signs and symptoms were correlated with imaging findings. RESULTS: Thirteen temporal bone meningiomas were reviewed in 8 women and 5 men, aged 18-65 years. Meningiomas were stratified into 3 groups on the basis of location and tumor vector of spread. There were 6 tegmen tympani, 5 jugular foramen (JF), and 2 internal auditory canal (IAC) meningiomas. Tegmen tympani and JF meningiomas were characterized by spread to the middle ear cavity. IAC meningiomas, by contrast, spread to the cochlea and vestibule. Hearing loss was the most common clinical presenting feature in all cases of temporal bone meningioma (10/13). The presence of tumor adjacent to the ossicles strongly correlated with conductive hearing loss (7/9). CONCLUSION: Meningioma involving the temporal bone is rare. Three subgroups of meningioma exist in this location: tegmen tympani, JF, and IAC meningioma. Tegmen tympani and JF meningiomas spread to the middle ear cavity. IAC meningiomas spread to intralabyrinthine structures. Conductive hearing loss is commonly seen in these patients and can be surgically correctable.

Adolescent↗