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Biomedical subjects

H Adams

Publications and source records attributed to H Adams.

At least 55 records · Page 3Linked to original sources
PubMed1993

The computed tomographic appearances in chronic berylliosis.

Computed tomography (CT) of the thorax was performed in eight patients with chronic berylliosis. The pulmonary CT features were variable and included pulmonary nodularity, and patterns consistent with upper lobe fibrosis or diffuse interstitial fibrosis. Mediastinal or hilar lymphadenopathy was shown in three cases. CT clearly demonstrates the pattern and distribution of pulmonary and mediastinal involvement in chronic pulmonary berylliosis but the appearances are non-specific.

Adult↗
PubMed1993

The computed tomographic appearances of angiosarcoma of the liver.

The computed tomographic (CT) appearances are described in five vinyl chloride workers with hepatic angiosarcoma subsequently confirmed at post-mortem. The tumour was multifocal in four patients. Non-enhanced scans were available in four cases showing hypodense masses relative to background liver. Dynamic scanning during intravenous contrast injection was performed in all five patients showing peripheral or central foci of enhancement within the tumour. On delayed post-contrast scans performed in three patients the angiosarcoma became wholly or partly isodense compared to normal liver. The CT appearances of angiosarcoma of the liver are non-specific but are consistent with a vascular tumour, and the differential diagnosis is discussed. Due to the vascularity of angiosarcoma, liver biopsy may be hazardous and can be avoided when there is a history of exposure to vinyl chloride monomer and the CT findings are consistent with the diagnosis.

Aged↗
PubMed1993

Energetics and kinetics of maltose transport in Saccharomyces cerevisiae: a continuous culture study.

In Saccharomyces cerevisiae, maltose is transported by a proton symport mechanism, whereas glucose transport occurs via facilitated diffusion. The energy requirement for maltose transport was evaluated with a metabolic model based on an experimental value of YATP for growth on glucose and an ATP requirement for maltose transport of 1 mol.mol-1. The predictions of the model were verified experimentally with anaerobic, sugar-limited chemostat cultures growing on a range of maltose-glucose mixtures at a fixed dilution rate of 0.1 h-1. The biomass yield (grams of cells.gram of sugar-1) decreased linearly with increasing amounts of maltose in the mixture. The yield was 25% lower during growth on maltose than during that on glucose, in agreement with the model predictions. During sugar-limited growth, the residual concentrations of maltose and glucose in the culture increased in proportion to their relative concentrations in the medium feed. From the residual maltose concentration, the in situ rates of maltose consumption by cultures, and the Km of the maltose carrier for maltose, it was calculated that the amount of this carrier was proportional to the in situ maltose consumption rate. This was also found for the amount of intracellular maltose. These two maltose-specific enzymes therefore exert high control over the maltose flux in S. cerevisiae in anaerobic, sugar-limited, steady-state cultures.

Adenosine Triphosphate↗
PubMed1993

Percutaneous needle biopsy of the mediastinum: review of 94 procedures.

BACKGROUND: A number of reports of radiologically guided percutaneous biopsy of mediastinal masses have been described but techniques have varied, particularly the type of needle used. In this study mediastinal biopsies with fine aspiration needles and cutting needles have been compared, sometimes in the same patient. The results are reviewed with particular emphasis on the choice of biopsy needle and its influence on pathological diagnosis. METHODS: A retrospective review was undertaken of radiologically guided mediastinal biopsies performed between 1981 and 1991. RESULTS: Sixty fine needle aspiration biopsies (FNA) and 34 Tru-Cut biopsies of mediastinal masses were performed in 75 patients with fluoroscopic or computed tomographic guidance. Overall sensitivity and specificity in terms of diagnosis of malignant disease were 90% and 100% respectively for FNA biopsies, and 96% and 100% for Tru-Cut biopsies. Diagnostic accuracy in terms of precise diagnosis of the malignant or benign nature of a mass and its origin was 77% for FNA biopsies and 94% for Tru-Cut biopsies. For FNA biopsies sensitivity and accuracy were higher for carcinomatous lesions (96% and 88%) than for noncarcinomatous lesions (81% and 69%). The only significant complication encountered was a pneumothorax following a biopsy which required intercostal drainage. CONCLUSIONS: Radiologically guided percutaneous needle biopsy is a safe procedure which provides useful diagnostic information in the majority of cases. Fine needle aspiration techniques usually suffice for carcinomatous lesions but a cutting needle biopsy should be performed whenever possible when lymphoma, thymoma, or neural masses are suspected to obtain larger specimens for more accurate histological diagnosis.

Adolescent↗
PubMed1993

Los Angeles organ sharing: twenty-six-year report.

1. The Los Angeles Transplant Society and the Regional Organ Procurement Agency of Southern California (ROPA) was established in November 1967. ROPA was the first such organization in the United States. 2. The use of simple cold storage and shipment of kidneys by commercial airline resulted from pioneering concepts developed in the Los Angeles area from 1968-1969. 3. In the 26-year period of ROPA's operation, it has coordinated 8,446 kidney transplants. 4. All kidneys transplanted in 1993 were allocated according to the UNOS point system. 5. Allocating all kidneys under the point system has not significantly disadvantaged either large or small transplant centers in the greater Los Angeles area. 6. Racial distribution of recipients: 13% Black (compared with Los Angeles population of 12% and 6% donor population). Blacks represent 20% of the recipient waiting list. Hispanic recipients were 31% (compared to Los Angeles population of 40% and donor population of 30%). Hispanics comprised 28% of the waiting list. 7. The average waiting times for centers in the Los Angeles area ranged from 14-19.4 months. Transplanted patients waited an average of 16.3-22.1 months. 8. "Required request" had a significant effect on the number of referrals but did not produce a meaningful increase in the number of kidneys transplanted.

Cryopreservation↗
PubMed1992

Computed tomographic assessment of patients following radical surgery for malignant mesothelioma.

Serial computed tomographic (CT) scans of the thorax and upper abdomen were performed in eight patients following radical surgery (pleuro-pneumonectomy) for diffuse malignant mesothelioma of the pleura. The post-operative appearances included a well defined membrane lining the pleuro-pneumonectomy space in seven cases; in two cases this resembled the original tumour. In six patients there was upward abdominal visceral displacement on the side of the surgery due to diaphragmatic resection; this resulted in contralateral mediastinal shift in four patients. One patient required a diaphragmatic prosthesis which produced a distinctive CT appearance. CT suggested recurrent mesothelioma in five cases. Although two patients had evidence of intrathoracic recurrence, in three patients the only feature was the non-specific finding of abdominal ascites. The normal CT appearances after pleuro-pneumonectomy should be recognized to facilitate radiological interpretation. With careful application CT is of value for the assessment of recurrent disease in patients following radical surgery for malignant mesothelioma.

Adult↗
PubMed1992

The sonographic appearances in postpartum thyroiditis.

During the postpartum period about 50% of women with circulating thyroid autoantibodies develop a transient autoimmune thyroiditis. To determine the sonographic appearances in postpartum thyroiditis (PPT), serial ultrasound (US) scans of the thyroid were performed in 135 postpartum women who were divided into three clinical groups: Group 1, 37 antibody positive subjects who developed PPT; Group 2, 28 antibody positive subjects in whom thyroid function remained normal; Group 3, 70 antibody negative controls. Thyroid hypoechogenicity was observed in 14/31 patients (45%) who were scanned between 4 and 8 weeks postpartum and who subsequently developed PPT (Group 1) compared with 4/24 patients (17%) in Group 2 (P less than 0.05) and 1/65 patients (1.5%) in Group 3 (P less than 0.001). In antibody positive patients, the positive predictive value of an abnormal scan during this period was 78%. Between 15 and 25 weeks postpartum thyroid hypoechogenicity was present in 32/37 patients (86%) in Group 1 compared with 11/28 patients (39%) in Group 2 (P less than 0.001) and 2/70 patients (3%) in Group 3 (P less than 0.001). Sonographic abnormality persisted beyond 32 weeks postpartum in 36/41 antibody positive patients (87%) who had exhibited thyroid hypoechogenicity earlier during the study and who had late scans. The characteristic US appearance in PPT is thyroid hypoechogenicity. The role of sonography in the prediction, diagnosis and follow up of patients with PPT is discussed.

Autoantibodies↗
PubMed1992

The computed tomographic appearances in pulmonary artery atresia.

Isolated pulmonary artery atresia is an uncommon congenital abnormality. Plain radiography and ventilation/perfusion lung scintigraphy may suggest the diagnosis but pulmonary angiography has traditionally been recommended for confirmation. The computed tomographic (CT) appearances of four patients with isolated atresia of a pulmonary artery are described. In each case the atretic segment of the abnormal vessel could be identified. Other CT findings included reduction of volume of the involved hemithorax, increased density of the affected lung, a small hilum, and an abnormal pulmonary vascular pattern thought to be due to the collateral systemic arterial supply to the intrapulmonary branches of the atretic pulmonary artery. The diagnosis of isolated pulmonary artery atresia can be made using dynamic, contrast enhanced CT without recourse to more invasive procedures.

Adolescent↗
PubMed1992

Massive pleural effusion: an unusual presentation of Castleman's disease.

Giant lymph node hyperplasia (Castleman's Disease) is a rare cause of pleural effusion. We report the case of a 51 yr old West Indian male, who presented with a recurrent massive pleural effusion, due to a tumour arising from the pleura. He underwent parietal pleurectomy and subtotal excision of the tumour. Histological analysis of the specimen showed the features of multicentric Castleman's disease. Nine months following surgery he remains well, with no recurrence of the effusion.

Castleman Disease↗
PubMed1991

An appraisal of CT pulmonary density mapping in normal subjects.

Modern computed tomographic (CT) scanners have post-processing facilities which allow pixels within a selected density range to be highlighted. It has been suggested that using this technique to highlight regions of low CT density (-900H to -1000H) can locate and quantitate areas of pulmonary emphysema. To establish the variability of the lung density map in normal subjects this technique was used in 17 patients with no evidence of structural lung disease on full respiratory function testing. Mean CT lung density varied from -770H to -875H (overall mean -817H). The percentage cross-sectional area in the low density range -900H to -1000H varied from 0.6% to 58% (mean 15.3%). In two further groups of 12 subjects the influence of CT slice thickness and intravenous contrast administration on the lung density map was evaluated. The use of narrower collimation led to an increase in mean cross-sectional area within the low density range from 9.6% to 16.1% (P less than 0.05). The use of intravenous contrast led to a reduction in mean cross-sectional area within the range from 8.9% to 3.3% (P less than 0.01). There is considerable variability in the lung density map of normal individuals and the method is also dependent on radiographic technique. These factors should be taken into account when considering the use of CT lung density mapping for the assessment of pulmonary disease.

Adult↗
PubMed1991

Computed tomography of the brain: does contrast enhancement really help?

The contribution of intravenous contrast medium to the final diagnosis was assessed in 300 patients undergoing routine axial computed tomography (CT) of the brain. Two-hundred-and-twelve patients presented with symptoms or signs suggesting focal intracranial pathology and 88 with non-focal features. A total of 110 post-contrast scans were abnormal. The differential diagnosis was altered in 15 patients (5%) following contrast enhancement, 13 of whom presented with focal symptoms and signs. In three patients with normal plain scans and symptoms and signs suggesting focal intracranial pathology abnormalities were only seen after contrast medium and in only one was the lesion surgically treatable. In a further 15 patients (5%) contrast enhancement increased the certainty of the diagnosis that had been made on the uncontrasted scan. We feel that when the uncontrasted scan is normal contrast enhancement is only helpful in a limited number of patients with symptoms and signs suggesting focal intracranial pathology. Contrast enhancement is still important in differentiating abnormalities seen on the unenhanced scan even with modern high resolution CT scanners.

Brain↗
PubMed1991

Case report: gastroduodenal intussusception--an unusual cause of pancreatitis.

Gastroduodenal intussusception is a rare complication of polypoidal gastric tumours, and it has not previously been described as a cause of acute pancreatitis. We report a case of an endoscopically, radiologically and histologically proven intussuscepting gastric leiomyoma presenting with biochemical evidence of acute pancreatitis. The radiological appearance is illustrated and possible mechanisms for the pancreatitis are discussed.

Acute Disease↗
PubMed1989

Hyperdense middle cerebral artery: incidence and quantitative significance.

The hyperdense middle cerebral artery sign (HMCAS) is recognized as a CT finding that indicates thrombus or embolus within the middle cerebral artery. The incidence and significance of this sign are quantitatively evaluated in 50 patients entered into experimental drug studies for treatment of cerebral infarction.

Acute Disease↗