Search PubMed⌕ Search

Biomedical subjects

D M Williams

Publications and source records attributed to D M Williams.

At least 289 records · Page 16Linked to original sources
PubMed1987

Assessment of portosystemic shunt patency and function with magnetic resonance imaging.

Magnetic resonance imaging (MRI) was performed in seven patients before and after portosystemic shunting to evaluate venous changes accompanying nonselective and selective shunt construction. The size and number of the intrahepatic portal and hepatic veins, left perirenal veins, and left upper quadrant varices were evaluated at MRI before and after shunt construction. MRI correctly diagnosed patent shunts in all seven patients. A marked decrease in the size of intrahepatic veins after a total or nonselective shunt suggests adequate portal vein and variceal decompression. Dilatation of left perirenal veins in the presence of a patent mesorenal or splenorenal shunt suggests hypertension of the left renal vein and possibly inadequate decompression of esophageal varices.

Adult↗
PubMed1986

Early variceal rebleeding after successful distal splenorenal shunt.

Of 77 patients with repeated variceal hemorrhage who underwent distal splenorenal shunt, five (6.5%) developed rebleeding despite a patent splenorenal anastomosis. Three of the five patients died. Early variceal rebleeding usually indicates shunt thrombosis but may occur with a patent anastomosis. Anatomic or functional left renal vein and/or splenic vein hypertension producing incomplete variceal decompression is generally the cause. Ineffective separation of the main portal vein from the gastrosplenic venous plexus may coexist and further intensify variceal congestion. Urgent angiographic studies and direct shunt catheterization with measurement of splenic vein, left renal vein, and inferior vena cava pressures should be performed to plan appropriate therapy. A significant gradient between the splenic and renal veins is evidence of an unsatisfactory anastomosis and should be managed by balloon angioplasty or reoperation. High splenic and left renal vein pressures with a gradient of more than 10 mm Hg between the renal vein and the inferior vena cava indicate renal vein hypertension. Initial therapy should include serial injection sclerotherapy, as renal vein hypertension will usually resolve over time as additional collaterals develop. However, persistent or recurrent variceal hemorrhage may require total portal decompression to bypass the restrictive left renal vein segment.

Adult↗
PubMed1986

Effects on mastitis of overmilking in conjunction with pulsation failure.

Half-udder comparisons were made using 56 cows for 2 months, in an experiment involving high bacterial challenge, to assess the combined effects of 5 min overmilking and pulsation failure (resulting from the use of shortened teacup liners) on teat condition and mastitis. Only three new infections were confirmed in over 12500 quarter milkings in quarters milked with control liners (of 148 mm effective length) indicating little or no effect of prolonged overmilking in these quarters. A 3.5-fold increase in the new infection rate (NIR) based on bacteriological diagnosis alone (P less than 0.01), or a 9-fold increase in NIR based on bacteriological diagnosis plus raised cell count and/or N-acetyl-beta-D-glucosaminidase (P less than 0.01), occurred in quarters milked with the same liners shortened to an effective length of 120-130 mm. The mean interval to infection or teat canal colonization (41 v. 60 milkings), and for a quarter infection to be confirmed by other diagnostic tests (45 v. 79 milkings) was significantly less in quarters overmilked with short liners. The results confirm that NIR increases whenever pulsation fails. Overmilking may increase NIR when it is associated with pulsation failure.

Animals↗
PubMed1986

The bovine teat canal: information from measurement of velocity of milk flow from the teat.

The velocity of milk flow from the teat during the peak flow rate period of milking was estimated to be approximately 8.5 m/s with a liner vacuum of 50 kPa and 7.5 m/s at 40 kPa. These results confirm the applicability of the Bernoulli theorem for estimating velocity of milk flow through the teat canal during milking. Concurrent measurements of mass flow rate and velocity indicate that the effective diameter of the open teat canal is approximately 2 mm. Further calculations indicate that the shear force due to milk flow acting to debride the surface of the open teat canal is about 1.8 X 10(-2) N. The opposing surfaces of the 'closed' teat canal may be approximately 100 micron apart immediately after milking. If so, bacteria present in the milk residue within the teat canal would never be more than 50 micron from a surface.

Animals↗
PubMed1985

Reduced levels of plasma ascorbic acid (vitamin C) in sickle cell disease patients: its possible role in the oxidant damage to sickle cells in vivo.

The role of oxidant damage to red cells in sickle cell disease has been of interest in recent years. Ascorbic acid is a well known antioxidant. The present study found that sickle cell patients have low levels of plasma ascorbic acid. In addition, it was observed that the pretreatment of sickle cells with ascorbic acid protects their membranes against in vitro peroxidative lipid damage induced by their exposure to hydrogen peroxide. The data suggest that low plasma ascorbic acid levels in sickle cell patients may be a factor in the increased vulnerability of sickle cells to oxidant damage in vivo.

Anemia, Sickle Cell↗
PubMed1985

Familial hyperparathyroidism associated with cementifying fibromas of the jaws in two siblings.

Two brothers affected by primary hyperparathyroidism, both with unusual jaw lesions, are described here. The atypical growth patterns of these lesions led to their surgical exploration, which revealed that they were histologically similar benign fibro-osseous lesions. The possible influence of long-standing metabolic alterations in hyperparathyroidism in the genesis of fibro-osseous lesions is discussed.

Adult↗
PubMed1985

Malignant fibrous histiocytoma of the maxilla. Case report and review of the literature.

A case of malignant fibrous histiocytoma (MFH) occurring in the maxilla is presented. Although MFH is now recognised as the most common soft tissue sarcoma of late adult life, it rarely occurs in bone and then more usually in the long bones. Presentation affecting the facial bones and skull is extremely rare, but should be considered in the differential diagnosis of bone tumours affecting the maxilla. Skeletal lesions appear more aggressive than those in soft tissues. Early radical excision is the treatment of choice although radiotherapy for inoperable tumours may lead to regression, as in the case presented here.

Adult↗
PubMed1985

The effect of iron substrate on mitochondrial haem synthesis in copper deficiency.

Studies of iron utilization and haem synthesis were carried out with hepatic mitochondria obtained from copper-deficient and pair-fed control rats. Ferric chloride can be used as Fe substrate for mitochondrial haem synthesis in the presence of succinate. Utilization is further enhanced by the addition of FMN. Ferritin does not support haem synthesis in the presence of succinate alone, but does support haem synthesis when FMN is added. Mitochondrial haem synthesis is impaired in Cu deficiency when either FeCl3 or homologous ferritin is used as Fe substrate. The results of the present study suggest that impaired haem synthesis in Cu deficiency occurs at a step following the chemical reduction of Fe substrate.

Animals↗
PubMed1985

Malignant histiocytosis appearing as cold-agglutinin disease.

We have described a 63-year-old man with elevated titers of cold agglutinins who was found to have malignant histiocytosis. Treatment with cytotoxic agents resulted in a rapid though temporary clinical response. Malignant histiocytosis should be considered in patients with unexplained cold agglutinin disease.

Agglutinins↗
PubMed1985

Hepatic falciform artery: anatomy, angiographic appearance, and clinical significance.

Three patients developed supraumbilical skin rashes during hepatic artery infusion chemotherapy by a surgically placed perfusion catheter and drug-infusion pump. In one patient, hepatic arterial scintigraphy with technetium-99m macroaggregated serum albumin showed increased uptake corresponding to the rash, and a hepatic arteriogram showed a dilated falciform branch of the left hepatic artery. Surgical ligation of the falciform artery permitted further treatment without recurrent rash. Based on a review of 100 celiac arteriograms, the incidence of the falciform artery on angiographic studies is approximately 2%. The angiographic appearance of this artery is presented, and its potential clinical significance in hepatic artery perfusion chemotherapy is discussed.

Abdominal Muscles↗
PubMed1985

Portal hypertension evaluated by MR imaging.

Thirteen patients with portal hypertension were examined by magnetic resonance (MR) imaging, using spin-echo sequences, and by visceral angiography. Data from this group were compared with the MR images and angiograms of 20 patients without portal hypertension. MR imaging demonstrated two of three cases of portal vein occlusion and four of five cases of occlusion of the retropancreatic portion of the superior mesenteric vein. Two thirds of the patients with portal hypertension and patent portal veins had marked MR signal within the main portal vein on MR images. Little or no signal was present in the portal veins of the 20 patients without portal hypertension. Our experience indicates that marked intraportal MR signal can be seen in patients with portal hypertension with or without venous occlusion. In some cases the size and distribution of venous collaterals allow one to distinguish between venous occlusion and other causes of portal hypertension. MR images confirmed the patency of distal splenorenal shunts in two patients studied.

Adult↗
PubMed1985

Adrenal pseudomasses due to varices: angiographic-CT-MRI-pathologic correlations.

Periadrenal and adrenal portosystemic collaterals are a recently reported cause of adrenal pseudotumor on computed tomography (CT). Nine patients with this left adrenal pseudotumor illustrate its typical position and appearance on CT, angiography, CT-angiography, and magnetic resonance imaging (MRI). The anatomic basis for variceal adrenal pseudotumors is the left inferior phrenic vein, which passes immediately anterior to the left adrenal gland and which serves as a collateral pathway from splenic to left renal vein in portal hypertension. Thus, unlike previously described adrenal pseudotumors, these venous collaterals are not anatomically distinguishable from the adrenal gland on CT. Bolus dynamic CT is usually diagnostic, but in equivocal cases, MRI may prove useful.

Adrenal Gland Neoplasms↗
PubMed1985

Skin diseases and the dry eye.

Patients with oral cicatricial pemphigoid, who present to an oral medicine department, should be examined by an ophthalmologist because over 65 per cent have been found to have an asymptomatic cicatrising conjunctivitis. Early detection and treatment of these patients may help to slow down the scarring process that eventually leads to a dry eye and blindness. The same is true for a group of patients who present to the dermatologist with a non-scarring bullous dermatosis distinguished by the presence of a linear deposit of IgA along the dermo-epidermal junction of uninvolved skin examined by direct immunofluorescence. The cicatrising conjunctivitis found in about 50 per cent of adults with this condition is indistinguishable from that of cicatricial pemphigoid. Ten per cent of patients with cicatricial pemphigoid affecting mucous membranes alone were found to have linear deposits of IgA along the dermo-epidermal junction of uninvolved skin. This suggested that there may be a common pathogenic pathway with varying clinical expression in these groups of patients and presents new possibilities for therapy in some patients with cicatricial pemphigoid.

Adolescent↗