A technique for the chronic study of the hepatic uptake and excretion of substances in the conscious pig

The pig is an ideal animal for studies of hepatic metabolism and the handling of drugs by the liver because of the many similarities in liver function to that in man. In this report we describe for the first time, in this animal, methods for the chronic implantation of sampling catheters in the major hepatic vessels and for the construction of an external biliary shunt. This model has many advantages in that it permits in the conscious animal intermittent, simultaneous and precise sampling of the hepatic uptake and clearance of substances and intermittent sampling of bile, without permanent interruption of the enterophepatic circulation. The effectiveness of this preparation has been assessed in 55 pigs. It was demonstrated that the majority of catheters remained patent for at least three days and in many cases for much longer. No significant alteration in liver function could be shown for at least seven days after surgery.

Cardiovascular complications during prolonged starvation

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The experimental assessment of techniques of measuring biliary pressure

A variety of different methods have been used for the measurement of pressures during operations on the biliary tract. However, there are few data on the experimental evaluation of the methods, and there has been no controlled comparative evaluation of the most commonly used techniques. In these experiments, we have compared the manometric technique of Caroli, the syringe barrel method of Daniel and White et alii, and the constant infusion apparatus of Cushieri. The experiments were performed in pigs because of the similarity of their biliary tract to that of man. Resting and opening pressures were recorded, and flow into the duodenum via the ampulla was measured simultaneously. The manometric and syringe barrel techniques gave highly reproducible measurements of resting and opening pressure, and valid measurements of opening pressure. The constant infusion apparatus gave reproducible measurements of resting pressure, but did not measure opening pressure. The manometric technique was shown to measure changes in the resistance of the choledochoduodenal junction in response to morphine and atropine.

Measurement of serum folate by 75Se-selenofolate radioassay. Results of a multi-institutional clinical trial

The authors report the multi-institutional evaluation of a radioassay for serum folate utilizing a gamma-labeled folate analog (75Se-pteroyl-L-methylselenocysteine). The assay is run as a one-step simultaneous addition at ambient temperature and is completed within 45 minutes. The assay data were reproducible within four study centers and correlated with both the Lactobacillus casei diagnostic groups and the clinical pictures.

Aniridia, cataracts, and Wilms' tumor in monozygous twins

We studied the first instance of aniridia-Wilms' tumor syndrome in twins who were mentally retarded. Both of them had congenital aniridia, cataracts, and glaucoma; only one subsequently developed a Wilms' tumor. A two-allele, two-step mutation is the most likely explanation of this genetically abnormal syndrome in twins. The aniridia-Wilms' tumor syndrome in twins further documents the relationship of teratogenic malformations and neoplasias.

Reinterpretation of the haematological effects of anticonvulsant treatment

Blood-counts and folate assays were performed on samples from 102 adults at a residential institution for severe mental impairment. 96 of these patients were receiving anticonvulsant therapy and 6 were not. Only 1 subject had a macrocytic blood-picture, and 5 subjects had hypochromic anaemia. No features of incipient metaloblastic haemopoiesis were identified in the remaining samples. However, serum-folate measured by two assay methods was subnormal in 83% of the samples; red-cell folate was subnormal in 40%. It is concluded that the development of macrocytic anaemia in subjects on long-term anticonvulsants therapy is probably not related to the biochemical process which causes their low assayable folate but reflects inadequate nutrition.

Measurement of red cell folate with 75Se-selenofolate radioassay

75Se-selenofolate radioassay was adapted for the purpose of red cell folate measurement. The results of assay of 124 whole blood samples by Lactobacillus casei microbiological assay and by radioassay using the adapted selenofolate method were concordant (r = 0.8). Red cell folate levels by the radioassay were below 170 microgram/1 in people who had haematological features of folate depletion. The distribution of results among reputedly healthy subjects extended down to 140 microgram/1.

Measurement of serum folate: experience with 75Se-selenofolate radioassay

Three hundred and eighty-two serum samples were assayed for folate content by a standard Lactobacillus casei microbiological assay and by radioassay using the 75Se-selenofolate radioassay kit from the Radiochemical Centre, Amersham. Results showed encouraging concordance. Explanations were discovered for the few disparities. The radioassay procedure is simple and an assay batch can be completed in one working day.

Vitrophage in management of congenital cataracts

We have used the vitrophage for combined lensectomy and vitrectomy in six eyes with congenital cataracts. No intraoperative complications were encountered. One week after operation four of the six eyes had clear corneas, and all eyes showed a bright red reflex. With follow-up ranging from 18 to 21 months all eyes had clear corneas and a view of the posterior pole consistent with 20/20 vision.

Cultured thyroid cell adenosine 3',5'-cyclic monophosphate response to thyrotropin: loss and restoration of sensitivity to iodide inhibition

Unlike in all other thyroid preparations, exposure of dog thyroid cells in long-term monolayer culture to iodide (10(-7) to 10(-3) M for up to 19 h did not blunt the subsequent adenosine 3', 5'-cyclic monophosphate (cAMP) response to thyrotropin (TSH) stimulation. This lack of effect of iodide was observed even when confluent thyroid cells were "follicularized" by the action of TSH in the culture medium. Preincubation of these cells in thyroxine (T4) and triiodothyronine (T3) was similarly without effect on the subsequent cAMP response to TSH. Study of thyroid cells during the early phase of primary culture demonstrated that inhibition by iodide (10(-4) M) of the cAMP response to TSH occurred after 7 h but was lost after 48 h of cell culture. This inhibitory effect of iodide was prevented by the inclusion of methimazole in the preincubation medium. As with iodide-insensitive cells, T4 and T3 were without effect on the cAMP response to TSH in iodide-sensitive thyroid cells. Exposure of iodide-insensitive thyroid cells to iodide-containing medium obtained after 2 h of incubation with dog thyroid slices, as well as to medium enriched with the 100,000 g supernatant fraction of homogenates prepared from these thyroid slices, did not restore the inhibitory action of iodide. However, iodide-sensitivity of the cAMP response to TSH was restored by preincubation of iodide-insensitive cells in 10(-4) M iodide plus an H2O2-generating system (glucose-glucose oxidase). These data suggest that T4 and T3 are not organic iodine inhibitors of the thyroid cAMP response to TSH. In addition, they provide evidence against the existence of a soluble, freely diffusible, organic iodine inhibitor of thyroid adenylate cyclase. The loss of sensitivity to iodide inhibition of adenylate cyclase that occurs in thyroid cells shortly after initiation of primary culture appears to be related to a defect in the cellular organification mechanism, possibly the H2O2-generating system.

Case reports and studies of paraneoplastic hypotension: abnormal low pressure baroreceptor responses

Intrathoracic stretch receptors regulate adjustments of the vasculature to gravitational changes and influence urinary water and solute excretion. Few reports of pathologic states involving interruption of these regulatory mechanisms have appeared. Two patients with orthostatic hypotenstion related to advanced intrathoracic carcinoma were studied, utilizing tilt-table examinations and immersion of the entire body in water to test the function of their intrathoracic baroreceptor reflex arcs. Both patients showed abnormalities of antidiuretic hormone level and sodium excretion as compared with normal controls. This suggests that total immersion is a safe and convenient test of the low-pressure baroreceptor system in patients with suspected dysfunction. Three patients are also reported whose charts were reviewed posthumously. Although they were not tested in the laboratory, their clinical data suggest that they too had been suffering from an interference with the transmission of impulses from the intrathoracic receptors.

The influence of duration of circulatory arrest at 20 degrees C on cerebral changes

In infants and piglets subjected to periods of circulatory arrest at 20 degrees C there was close correlation between duration of arrest and delay in return of electroencephalographic activity. Post mortem studies demonstrated histological evidence of brain damage in patients after circulatory arrest at 20 degrees C. Similar histological changes were demonstrated in piglets, including some who had complete E.E.G. and clinical recovery from circulatory arrest.

Intravitreal antibiotic injection and vitrectomy in acute bacterial endophthalmitis

Two days after an unplanned extra-capsular cataract extraction with sector iridectomy, a patient showed typical signs of bacterial endophthalmitis. Vitreous and aqueous were aspirated for culture, and gentamicin and dexamethasone were injected. Twenty-four hours later, after isolation of Staphylococcus epidermidis, a vitrectomy to remove the central vitreous was done. Postoperatively, vision progressively improved; at the last review nine months after vitrectomy, visual acuity was 20/50.

Effects of intravenous glucose during pacing-induced angina pectoris in patients with coronary artery disease

The effects of hypertonic glucose infusion on the anginal threshold determined by atrial pacing was studied in 14 patients with significant coronary artery disease. After glucose, angina occurred at a significantly lower heart rate and double product (systolic arterial pressure x heart rate), suggesting a decreased tolerance to ischemic stress. No stoichiometric relationship was noted between glucose uptake and lactate production, and there was no evidence that hypertonic glucose infusion resulted in enhanced anaerobic glycolysis in the ischemic myocardium. Acute elevation of plasma glucose levels may not be beneficial to patients with coronary artery disease.

Cataract extraction by the intracapsular methods and by phacoemulsification: the results of surgeons in training

The results of 63 phacoemulsifications performed by 14 resident ophthalmologists (surgeons in training) were compared to their first 112 intracapsular cataract procedures. Although the number of complications was greater in the eyes undergoing intracapsular operations, the final visual acuities obtained by either procedurewere similar: visual acuities in the range of 20/20 to 20/30 were found in 80.7% of intracapsular cataract operations and in 83.3% of phacoemulsification procedures. Visual acuities of 20/50 or better were found in 90.3% of intracapsular cataract extractions andin 88.8% of phacoemulsification procedures. Cylindric correction of higher power was required to correct astigmatism associated with intracapsular cataract surgery as compared to phacoemulsification. The results of irrigation-aspiration of soft or traumatic cataracts performed in 20 eyes with needle and syringe were compared to results of 19 eyes operated on by use of the Cavitron-Kelman irrigation-aspiration handpiece. The incidence of postoperative secondary membrane requiring discussion was similar for both procedures. The basis for setting up a successful program for resident training in phacoemulsification is discussed.