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Biomedical subjects

F L Weber

Publications and source records attributed to F L Weber.

49 records · Page 3Linked to original sources
PubMed1980

Gelatinous drop-like dystrophy. A form of primary corneal amyloidosis.

A keratoplasty was performed on the right eye of a 12-year-old boy affected by gelatinous drop-like corneal dystrophy. This rare form of primary corneal amyloidosis has been more often reported in Japanese than in occidental literature. In the case presented here, the occasional fusiform deposits of amyloid observed in the stroma suggest a relationship between gelatinous drop-like corneal dystrophy and lattice dystrophy. A new classification of the different types of primary corneal amyloidosis is proposed.

Adolescent↗
PubMed1979

Corneal trauma from projection of metallic mercury into the eyes.

A 24-year-old woman sustained bilateral ocular lesions due to projection of mercury into the eyes during an explosion in a chemical laboratory. A lamellar keratectomy was performed on the right eye four hours after the accident, and 12 days later, the same procedure was performed of the left eye. Studies by light and electron microscopy were done on both specimens. The essential findings were total loss of epithelium, necrosis of keratocytes, absence of inflammatory reaction, and absence of superficial stromal repair in the specimen that was obtained 12 days after the accident. These findings indirectly confirm the importance of epithelium and normally vascularized conjunctiva in healing wounds of the cornea.

Adult↗
PubMed1979

The effect of lactulose on urea metabolism and nitrogen excretion in cirrhotic patients.

The mechanism of action of lactulose is not known, although in vitro evidence suggests that lactulose may increase ammonia utilization and decrease ammmonia production by gut flora. If these changes occur in patients, they should be reflected in altered urea metabolism and nitrogen excretion. In seven studies conducted in 6 cirrhotic patients, the effects of lactulose on the kinetics of urea metabolism and nitrogen excretion were determined. Lactulose caused a fall in urea production (-24%, P less than 0.005) that was reflected in a decrease in both urea degradation and urinary urea excretion. Likewise, lactulose caused a decrease in the total body urea pool. The fall in urinary urea was accompanied by a large (two- to threefold) increase in stool nitrogen that was of a similar magnitude of the fall in urinary urea. Although urea degradation fell after lactulose, the intestinal (extrarenal) clearance of urea did not, indicating that the fall in urea degradation was due to the observed fall in the urea pool. The results indicate that: (a) Lactulose decreases urea production by increasing the fecal output of nitrogen, a finding compatible with altered ammonia metabolism by gut flora. (b) Lactulose decreases urea degradation, although this effect is primarily the result of a fall in the urea pool and cannot be attributed to an inhibition of urea breakdown in the gut lumen.

Aged↗
PubMed1979

Abnormalities of hepatic mitochondrial urea-cycle enzyme activities and hepatic ultrastructure in acute fatty liver of pregnancy.

Two patients presenting with acute fatty liver of pregnancy were studied. Because of similarities between acute fatty liver of pregnancy and Reye's syndrome, we investigated hepatic ultrastructure, urea-cycle enzyme activities, and plasma amino acids. Initial liver biopsies obtained 12 and 21 days after the onset of illness demonstrated microvesicular fat deposition and mitochondrial ultrastructural changes, including pleomorphism and abundant crystalline inclusions. In both biopsies, activity of the mitochondrial urea-cycle enzyme OTC was markedly below normal limits. Activity of the other mitochondrial urea-cycle enzyme, CPS, was low in one patient. Abnormalities of these enzymes persisted in second biopsies obtained at 9 and 28 weeks, respectively. By 44 weeks all urea-cycle enzyme activities had returned to normal in one patient. However, in the other patient OTC activity was still reduced at 52 weeks, although it had doubled in comparison to previous biopsies. Morphological changes of the mitochondria generally improved in parallel with the urea-cycle enzymes. Plasma amino acids, obtained at the time of the initial biopsies, demonstrated a generalized hypoaminoacidemia with the exception of glutamate. Serial observations in patients with this rare disease indicate that there are similarities with Reye's syndrome, in particular, reduced activity of the mitochondrial urea-cycle enzymes. But there are important differences. (1) Enzymatic and ultrastructural abnormalities of mitochondria persist for a longer period of time than in Reye's syndrome. (2) Mitochondrial ultrastructure is different. (3) Plasma amino acid profiles are different.

Acute Disease↗
PubMed1978

Corticosteroid therapy of alcoholic hepatitis.

Fifty-five patients with alcoholic hepatitis were studied in a 28- to 32-day randomized double blind treatment trial comparing prednisolone (40 mg per day) with placebo therapy. Of 31 placebo-treated patients, 4 died during the study interval and 2 more died within 5 days of study completion. Only 1 of 24 prednisolone-treated patients died during the same interval (Fisher exact test; P = 0.10). Stepwise discriminant analysis of laboratory factors associated with death revealed independently significant associations with prolongation of prothrombin time and height of serum bilirubin at the initiation of the study. When treatment was included as a variable in this discriminant analysis, it was found that corticosteroid therapy significantly decreased mortality (P less than 0.05). The corrected wedged hepatic venous presure decreased to a similar extent in the two groups. These studies suggest that corticosteroid therapy does decrease early mortality in patients with severe alcoholic hepatitis, but has no short term effect on the development of portal hypertension.

Adult↗
PubMed1977

Amino acid metabolism of dog jejunum before and during absorption of keto analogues.

In fasting dogs, significant uptake by the jejunal wall from arterial blood was found for glutamine and eight other amino acids. Significant release into the mesenteric vein of ammonium, alanine, citrulline, and proline occurred, equal in nitrogen content to glutamine nitrogen taken up. The keto analogues of leucine, valine, and isoleucine, infused for 1 h into the lumen at initial concentrations of 10mM, disappeared from the lumen at 20.2 +/- 1.6, 18.6 +/- 2.0, and 15.7 +/- 2.8 mumol/cm in 1h, respectively. Eight fifteen and seventeen percent, respectively, of these absorbed quantities were released into mesenteric blood as leucine, valine, and isoleucine plus alloisoleucine, indicating significant amination of the keto acids by the gut wall. No significant changes were detected in the arteriovenous differences of any other amino acids or ammonium. The remainder of the absorbed analogues of valine and isoleucine appeared as such in the blood. In the case of the keto analogue of leucine, there was apparent degradation by the gut wall of 34% of the absorbed compound.

Amino Acids↗
PubMed1976

Effects of keto analogues of essential amino acids in portal-systemic encephalopathy.

Keto analogues of five essential amino acids (valine, leucine, isoleucine, methionine, and phenylalanine) were given either parenterally or orally in varying proportions to 11 patients with portal-systemic encephalopathy and hyperammonemia. Plasma concentrations of amino acids corresponding to the infused analogues, including alloisoleucine, increased significantly after infusions. Plasma tyrosine and glycine, which were abnormally elevated in control samples, fell after the infusions. After one to five daily infusions, the ratio of essential to nonessential amino acids in fasting plasma was increased toward normal, suggesting improved protein nutrition. Arterial blood ammonia and glutamate did not change immediately after infusions, but a pronounced decrease in glutamine (42%) was observed. Eight nitrogen balance studies performed in 5 patients during 3 to 12 days of oral or intravenous keto acid therapy failed to show consistent improvement in balance as compared with control periods. After five courses of oral therapy there was again significant improvement in the ratio of essential to nonessential amino acids. No toxicity from keto analogue administration was found, and clinical improvement, as assessed by mental status and psychological testing occurred in 8 of 11 patients. These studies suggest keto analogues of essential amino acids are converted to the corresponding amino acids in patients with portal-systemic encephalopathy, and that such therapy may be of benefit.

Administration, Oral↗