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Biomedical subjects

S B Lucas

Publications and source records attributed to S B Lucas.

At least 145 records · Page 8Linked to original sources
PubMed1985

Protection of sheep against Schistosoma bovis using cryopreserved radiation-attenuated schistosomula.

Three sheep were vaccinated with two doses of 3 krad-irradiated cryopreserved Schistosoma bovis schistosomula containing 20,000 and 17,000 organisms respectively, injected intramuscularly 23 days apart after storage in liquid nitrogen for between 9 and 46 days. A challenge of 5360 S. bovis cercariae was administered percutaneously approximately four weeks after the last vaccine dose to these animals and to three controls. Post-challenge the vaccinated animals gained significantly more weight (27% v. 9%), produced fewer eggs in their faeces, showed a smaller reduction in PCV values (-18% v. -27%) and were over-all in better condition than control animals. At perfusion 49.1% fewer adult worms were found in the vaccinated sheep than in controls. The tissue egg burdens were similar in both groups. Histopathologically both groups were similar except that fewer and smaller egg lesions were observed in the livers of vaccinated animals.

Animals↗
PubMed1985

Pathology associated with vaccination against Schistosoma mansoni in mice using cryopreserved radiation-attenuated schistosomula.

Twenty-one mice were injected intramuscularly with 2000 Schistosoma mansoni schistosomula irradiated at 20 krad and cryopreserved; three mice were killed on each of days 0, 2, 5, 9, 19, 28 and 44 days after infection and muscle from the site of injection in the left hind leg, the lungs and livers removed for histological examination. Schistosomula were seen in sections from the leg muscle from days 0 to 19 inclusive, in the lungs from day 2 to day 28 inclusive and in the livers from days 9 to 28 inclusive. Most schistosomula were seen in sections of the leg muscle with considerably fewer parasites occurring in the lungs and especially the livers. Granulomatous reactions comprising eosinophils, polymorphs, plasma cells and macrophages were first seen in the leg muscle on day 2, in the lungs on day 5 and in the liver on day 19. The peak inflammatory reactions appeared to occur between days 5 and 9, 9 and 19 and 28 and 44 respectively in the three tissues. The pathology is discussed in relation to the dose of irradiation required to attenuate the schistosomula for optimal immunogenicity.

Animals↗
PubMed1985

Hepatosplenic schistosomiasis in Kenya: an assessment of the enzyme-linked immunosorbent assay (ELISA).

Sera from 124 adult Kenyan patients with chronic splenomegaly and from 93 geographically matched controls without splenomegaly were tested for evidence of Schistosoma mansoni infection by enzyme-linked immunosorbent assay (ELISA). Ova of S. mansoni were detected on stool or rectal snip examination in 23.4% of all patients, whereas 57.3% had a positive ELISA. All patients with parasitological or histological evidence of schistosomal infection had a positive ELISA, and a negative test reliably excluded schistosomiasis. On the basis of liver histology, 23 patients (18.5%) were considered to have hepatosplenic schistosomiasis, of whom 17 (73.9%) had a positive stool or snip. The ELISA was positive in 47.5% of cases of non-schistosomal splenomegaly, and in 52.7% of apparently normal controls. This high seropositive rate in the latter two groups emphasizes that schistosomal infection does not signify disease, and limits the diagnostic value of the test in individual cases of splenomegaly. Marked tribal and, therefore geographical, differences were noted in the prevalence of infection.

Enzyme-Linked Immunosorbent Assay↗
PubMed1984

Analysis of circadian rhythms by fitting a least squares sine curve.

A method that fits a least squares sine curve to both point and averaged time series data is described. The method includes a full regression analysis and extends the current "cosinor" approach. Developments include estimation of the linear trend and fitting secondary wave forms.

Aged↗
PubMed1984

Computed tomographic appearances of cardiac amyloidosis.

Computed tomography was used to identify the characteristic appearances of histologically confirmed cardiac amyloidosis in two patients. Mean myocardial density and 95% confidence limits in one of these patients (30.6 +/- 3.4 Hounsfield units (HU) ) were significantly lower than in patients with diffuse hypertrophic cardiomyopathy (range from 38.8 +/- 5.7 HU to 45.9 +/- 4.4 HU) and normal myocardium (range from 41.9 +/- 4.3 HU to 44.8 +/- 4.4 HU) on pre-contrast computed tomograms. Although only an approximate myocardial density was obtained in the second patient with amyloidosis, a similar result (30 HU) was noted on pre-contrast tomograms. Diffuse thickening of the interventricular septum and left ventricular free wall was found in both patients. Myocardial density on post-contrast computed tomograms was 102.8 +/- 5.2 HU in one patient and approximately 100 HU in the other. A pericardial effusion was noted in the first patient. A low myocardial density on pre-contrast tomograms and diffuse myocardial thickening on post-contrast tomograms are considered to be important features of cardiac amyloidosis.

Alcoholism↗
PubMed1983

Pharmacokinetics of high-dose cyclophosphamide in patients with metastatic bronchogenic carcinoma.

Cyclophosphamide (CP) was administered to eight patients with metastatic bronchial carcinoma in escalating doses of 1.5, 2.5, and 3.5 g/m2 at intervals of 3 weeks. The proportion of the administered dose converted into alkylating metabolites was similar for each dose and there was no evidence to suggest that the enzyme system responsible for activating CP was saturated even with the highest dose. Considerable between-patient variation in drug metabolism was observed, but within each patient the fraction metabolised remained constant.

Adult↗
PubMed1983

Operative cholangiography: is there a statistical alternative?

Data from 424 patients who underwent cholecystectomy were analysed on a computer by both univariate and multivariate methods to determine the factors that identify patients with stones in the common bile duct. The presence of common bile duct stones was associated with increased age (p = 0.003), increased numbers of gallbladder stones (p less than 0.0001), a diagnosis of acute cholecystitis (p = 0.06), and a history of jaundice (chi-square = 22.2; p less than 0.001). A dilated common bile duct was the most significant indicator of the presence of stones (chi-square = 155.5; p less than 0.0001), and a dilated cystic duct was second (chi-square = 47; p less than 0.001). Using multivariate analysis, 89.5 percent of patients were correctly classified as having bile duct stones without the use of cholangiographic data (chi-square = 246.5; p less than 0.0001). Common bile duct diameter and the number of gallbladder stones emerged as the most important variables; additional historical factors, including the presence of jaundice and pancreatitis did not add to their predictive value. If multivariate analysis was used without cholangiographic data, bile duct stones would be missed in 3 percent of patients and unnecessary explorations would be carried out in 7.5 percent.

Adolescent↗
PubMed1983

Promotion of N-nitrosodimethylamine-initiated bile duct carcinogenesis in the hamster by the human liver fluke, Opisthorchis viverrini.

Four groups of male golden Syrian hamsters were treated as follows: Group I received 50 Opisthorchis viverrini metacercariae followed 41 days later by a single oral dose of 1.6 mg N-nitrosodimethylamine (NDMA). Group II received a single oral dose of 1.6 mg NDMA followed 96 h later by 50 O. viverrini metacercariae, Group III received a single oral dose of 1.6 mg NDMA only and Group IV 50 O. viverrini metacercariae only. Mortality was highest in Group I and II animals receiving both NDMA and parasites. Cholangiocarcinomas were discovered in five animals from Group I and in nine animals from Group II representing tumour incidences of 10% and 20%, respectively. None of the animals given NDMA alone (Group III) or parasites alone (Group IV) developed malignant bile duct tumours. The mean tumour latency period for Group I was 249 days (range 124--346 days) and for Group II 308 days (range 184--393 days). The difference for tumour latency between these two groups was not significant. Tumour was most frequently found in the right liver lobe, the lobe in the hamster which also contains the largest proportion of infecting O. viverrini worms. These results clearly indicate that an O. viverrini infection in the hamster host is capable of promoting NDMA-initiated bile duct carcinogenesis. These observations may bear some direct relevance to cholangiocarcinoma arising in association with Oriental liver fluke infection in man and may provide a useful tool for the study of an initiation-promotion system of aetiological significance for man.

Adenoma, Bile Duct↗
PubMed1983

Computed tomography: qualitative and quantitative recognition of liver disease in haemophilia.

Thirty haemophiliac patients have been investigated by computed tomography (CT). Quantitative studies using dual energy scans with and without contrast enhancement, together with autocorrelation function analysis of the characteristics of the liver and spleen, revealed significant changes in the liver. The CT findings corresponded to the presence of liver disease, including chronic active hepatitis and cirrhosis, in 13 patients confirmed by percutaneous liver biopsy.

Hemophilia A↗
PubMed1983

Portal hypertension in Nairobi, Kenya.

Previous reports have suggested that idiopathic portal hypertension, a condition quite distinct from tropical splenomegaly syndrome, occurs in Kenya. In the present study patients with oesophageal varices were allocated to diagnostic groups on the basis of liver histology and results of splenoportovenography , and these groups were then compared for prevalence of hepatitis B markers, immunoglobulin levels and results of enzyme-linked immunosorbant assay (ELISA) for S. mansoni infection. 85 patients with oesophageal varices were studied. 29.4% had histological evidence of Schistosoma mansoni infection, 20% had cirrhosis and in 25.9% liver histology was non-diagnostic and the portal vein was radiologically shown to be patent. A comparison of clinical findings, serological data and parasitological investigations suggested that this latter group was a distinct one, and did no result from failure of histological diagnosis of cirrhosis or schistosomiasis. It is likely that these patients had idiopathic portal hypertension. In 82 normal controls, the carrier rate of hepatitis B surface antigen (HBsAg) was 12.2%, 59.8% had antibody to HBsAg (anti-HBs) and 7.3% showed antibody to core antigen (anti-HBc) as the only viral marker. 58.3% of the cirrhotics and 26.7% of patients with probable idiopathic portal hypertension were HbsAg positive. The implications of these results, and limited data on hepatitis Be antigen and antibody are discussed.

Hepatitis B Surface Antigens↗
PubMed1983

The pathology in perinatal mortality in Nairobi, Kenya.

The clinico-pathological causes of death in 497 stillbirths and 1st 24 hour neonatal deaths in Nairobi are described. The major factors in stillbirth (303 cases) were cord compression and prolapse, birth trauma, and prolonged labour. Hyaline membrane disease and intraventricular haemorrhage caused death in 52% of the neonatal cases. The importance of intra-uterine infection is discussed.

Bacterial Infections↗