Rotating disk device for slit radiography of the chest

A pair of rapidly rotating disks was assembled with multiple radial slits for obtaining chest radiographs in 1/60-1/20 sec., using automatic exposure timing, without visible images of individual slits. Substantial reduction of scattered radiation levels is achieved (one half to one fourth), especially in the retrocardiac and central mediastinal areas of the chest film. Full realization of the potential contrast improvement resulting from this degree of scatter reduction is impaired by the limited latitude of x-ray films used for radiography. These problems and potential solutions are discussed.

A technique for peritoneal lavage without risk or complication

A technique for peritoneal lavage with an extremely low risk of complications has been developed. This technique has been used on 110 patients by 45 different physicians without morbidity.

Radiographic findings of the National Cooperative Crohn's Disease Study

On-study barium radiographs of 535 patients in the National Cooperative Crohn's Disease Study have been analyzed for the pattern of distribution of bowel disease and the individual features that characterized bowel involvement. On-study and off-study radiographs of 403 of these patients were compared under code to judge radiographic response to drug treatment and discover correlations of radiographic findings with clinical response. Patients with more clinically active disease had more colonic disease on x-ray. Duodenal abnormalities were recognized in 22% of the patients and radiographically typicaly Crohn's disease of the duodenum in 8%. Recurrent Crohn's disease and that characterized by small bowel obstruction each displayed a characteristic appearance. Overall there was little evidence of radiographic improvement during the study, and little correlation between clinical response and evidence of radiologic improvement. Only patients treated with prednisone for more than 6 mo showed statistically significant radiologic improvement. Patients with definite radiographic progression or regression were found in each treatment group. Both fistula and stricture with obstruction were associated with a poor clinical response to all therapies. In view of the evidence from this study that radiographic findings do not correlate with clinical symptoms or response, the ritual use of x-ray to follow patients with Crohn's disease is unnecessary.

Peritoneal lavage with low morbidity

Peritoneal lavage has proven to be a useful tool for evaluating abdominal trauma. However, morbidity levels associated with the technique have inhibited its wide acceptance. A technique has been developed that avoids the complications associated with use of a standard dialysis trocar or a mini-laparotomy. The technique uses an 18 gauge needle, a wire guide with soft tip and a number 9 French Teflon catheter. The test can be completed in 20 to 30 minutes and has been done in as little as seven minutes. This technique has been used by 51 different physicians in 132 cases with a single avoidable complication which occurred when one of the contraindications was violated.

Jejunal diverticulosis and chronic pneumoperitoneum

A unique case of pneumoperitoneum, without peritonitis or perforation, associated with jejunal diverticulosis is presented. Pneumoperitoneum is documented over the course of many years, with recurrence after partial small bowel resection. Jejunal diverticulosis is one of the leading gastrointestinal causes of pneumoperitoneum without peritonitis or surgery. The distended diverticular mucosa may function as a semipermeable membrane allowing transmural gas equilibration.

A model of biliary pancreatic reflux

A primate model for the study of biliary pancreatic reflux under relatively physiological conditions is described. Cannulas were inserted into the gallbladder and the common bile duct of rhesus monkeys, and a pedicled segment of small bowel was used to create a pancreaticocutaneous fistula after resection of the spleen and pancreatic tail. Following recovery, Hypaque was instilled into the gallbladder with maintenance of common duct pressure within a normal range. The pancreatic duct was visualized in 21 of 34 radiographic studies (19 monkeys). Small amounts of iodine were detected in the fistula effluent of nine of 11 animals that refluxed radiologically. Radioactive polyethylene glycol (PEG-C14) was instilled into the gallbladder and pancreatic fistula drainage sampled by aspiration (26 studies, four monkeys). When compared to controls without PEG instillation (six studies, four monkeys), there was a significant rise in fistula counts beginning 50 minutes after injection and peaking at 180 minutes. In a second series of studies, pancreatic fistula aspiration was replaced by a flush technique using a triple-lumen cannula which allowed constant monitoring and control of fistula pressure. A statistically significant rise and fall of radioactivity after PEG introduction again was demonstrated. These data demonstrate taht biliary pancreatic reflux can occur and be quantitated under these experimental conditions.

Rectal balloons: complications, causes, and recommendations

Nine previously unreported rectal injuries caused by barium-enema examinations have been reviewed. In each case, the injury occurred in conjunction with inflation of a rectal balloon. Analysis of the clinical material suggested that certain mechanical properties of balloon catheter tips might transfer mechanical stress to the rectal wall and contribute to the observed injuries. Careful manometric evaluation of in vivo rectal balloons suggest that significant anatomic differences in patients may be clinically important. Further experimental bench studies revealed undesirable mechanical properties in many commercially available rectal balloon catheters. These mechanical problems include low compliance, asymmetrical inflation, strong lateral and anterior displacement of a firm catheter tip into the restraining wall, and self-obstruction of the balloon deflation outlet by the inflated baloon. Many of these problems were clinically confirmed by careful in vivo observations and by evidence collected from the nine cases of rectal injury. A series of practical prophylactic procedures are recommended.

Peritoneal lavage with low morbidity

Peritoneal lavage has proven to be a useful tool for evaluating abdominal trauma. We developed a technique that avoids the complications associated with the standard dialysis trocar and the minilaporatomy. This technique has been utilized by 51 different physicians in 132 cases with a single avoidable complication. The bladder was entered when the rule of emptying the bladder first was violated.

Gossypiboma--the problem of the retained surgical sponge

Commonly used surgical sponges and appliances all have standardized, readily recognized opaque markers visible on radiographs. When these markers are identified on postoperative radiographs, they should be assumed to represent retained surgical sponges or appliances. With the rare exception of thoracotomy dressings, these marked materials are seldom, if ever, used as external bandaging materials. AP and lateral radiographs should provide an immediate answer as to the location of any retained surgical device. The early recognition of these retained surgical sponges should eliminate most complications related to their presence.

Aspirin effect on canine iopanoate transport maximun

Iopanoate saturation kinetics were measured in four dogs both drug free and following six days of low dose aspirin ingestion. Each animal acted as its own control. In post aspirin ingestion studies there was s significant (P less than .001) decrease in the apparent Vmax of iopanoate. The volume of distribution showed no significant change, and gallbladder visualization showed no significant change despite the decrease in Vmax. Although aspirin pretreatment decreases the control Vmax by 50%, its mechanism and significance in the clinical setting will require further study.

Limited effect of erythrocyte and plasma infusions in adenosine deaminase deficiency

A 10-month-old child with a profound deficiency of adenosine deaminase and severe combined immunodeficiency was treated for a period of 17 months with red cell and plasma transfusions containing normal amounts of the deficient enzyme. Following each transfusion, the plasma adenosine, red cell and lymphocyte ATP, urinary adenine, and urinary deoxyadenosine decreased transiently. During this period, the absolute blood lymphocyte count rose and a limited increased in the response of the lymphocytes to PHA-P was observed. Delayed hypersensitivity skin tests remained negative during the transfusion periods. A quantitative elevation of serum immunoglobulins occurred, but specific antibody formation was not elicited. In contrast to a previous report of successful therapy of ADA deficiency with red cell and plasma infusions, this patient responded poorly to enzyme replacement therapy. The difference may be related to a more profound enzyme deficiency in our patient.

Gastrointestinal angiographic findings in systemic amyloidosis

Amyloidosis is a multisystem disease process of unknown cause in which characteristically staining protein-polysaccharide material is deposited in body tissues. Although gastrointestinal involvement is usually asymptomatic, amyloid infiltration of mesenteric and submucosal vessel walls may be associated with acute or recurrent gastrointestinal hemorrhage in patients with the diagnosis of amyloidosis. Angiography in such cases may demonstrate arterial and venous changes as a result of these vascular wall deposits. Two patients with proven amyloidosis and gastrointestinal hemorrhage are presented, and their angiographic findings are discussed with the pathologic correlations.

Necrotizing enterocolitis in acute leukemia: radiographic findings

Acute gangrenous appendicitis or right lower quadrant necrotizing enterocolitis occurs with a high incidence in patients undergoing treatment for acute leukemia. In a series of 81 fully documented cases with complete charts and follow-up we identified seven surgically or pathologically proved cases of this syndrome. Plain radiographs of the abdomen were available in five of the seven cases, and a barium enema was performed on one. In three of the five cases the radiographic examination suggested or confirmed the nature of the right lower quadrant syndrome. Two of the seven patients were sucessfully treated by appropriate surgery. The radiographic findings in this series are reviewed and re-emphasized since an accurate diagnosis becomes important in appropriate management of this formerly uniformly fatal complication of acute leukemia and/or its therapy.

Estrogenic activities of chlorinated hydrocarbons

Some DDT analogs are estrogenic, particularly o,p'-DDT, which comprises approximately 15-20% of the commercial DDT mixture. Whether this compound or its metabolites are active has not been established. In fact, the data obtained thus far are more confusing than enlightening. For example, CCl4 pretreatment of immature female rats has been reported to inhibit or enhance estrogenic activity of o,p'-DDT, and SKF-525A pretreatment has been reported to enhance or not alter the estrogenic effect. Although o,p'-DDT inhibits binding of estradiol to the estrogen receptor from rat or human at low levels (approximately 1-10 micrometer) in vitro, higher levels are required to inhibit nuclear binding of [3H] estradiol in incubated whole uteri. Futhermore, o,p'-DDT appears to be neither estrogenic nor antiestrogenic in an in vitro estrogen assay. Methoxychlor appears to be "activated" by metabolism, and it is probable that phenolic metabolites are responsible for its estrogenic activity. Since chlorinated hydrocarbons often enhance the metabolism of steroids and may reduce circulating levels of steroids, interactions of the exogenous hormonally active agents with steroid receptors may be self-potentiating in vivo.

Retractile mesenteritis: initial presentation as colonic obstruction

Retroperitoneal fibrosis has been associated with a variety of sclerosing diseases. Among these is the variant known as retractile mesenteritis, which involves predominantly the mesentery of the small intestine and associated vessels; involvement of the mesocolon and the colon is less frequent. Two patients with a dominating clinical picture of colonic obstruction are described. The radiographic presentations were similar and should serve to remind radiologists and clinicians of this entity.

Analysis of methotrexate in human plasma by high-pressure liquid chromatography with fluorescence detection

Methotrexate in human plasma at a concentration as low as 0.01 microgram/ml can be assayed with the use of high-pressure-liquid chromatography and a fluorescence detection system. Methotrexate is oxidized stoichiometrically to 2,4-diaminopteridine-6-carboxylic acid, a fluorescent product that is separable from other fluorescent materials in plasma with the use of an octadecylsilane (reversed phase) column. The detector response is linear over the range of 0.01 to 10 microgram/ml. Neither folic acid nor citrovorum factor interferes with the analysis. N-((4-([2,4-Dihydroxy-6-pteridyl)methyl]-amino)benzoyl))glutamic acid may be used as an internal standard, since it can be extracted from plasma and oxidized like methotrexate. The procedure is rapid (about 30 min) and should be a useful method for monitoring methotrexate plasma concentrations.

Increased purine nucleotides in adenosine deaminase-deficient lymphocytes

It was found that ATP and cyclic AMP were greatly increased in human blood lymphocytes which were deficient in ADA. Certain other purine and pyrimidine nucleotides were elevated but to a lesser degree. Energy production in these cells may be inhibited by the increase in nucleotides since the ATP:ADP ratio was significantly below normal. Thus it appears that the immunologic deficiency in human ADA deficiency is related to increased nucleotide concentrations in the lymphocytes.

Mechanism of action of 2-amino-1,3,4-thiadiazole (NSC 4728)

The synthesis and isolation of two derivatives of 2-amino-1,3,4-thialdiazole(aminothiadiazole) are described. The derivatives are a nicotinamide adenine dinucleotide (NAD) analog prepared by an exchange reaction with NAD in the presence of nicotineamide adenine dinucleotide glycohydrolase and a presumed aminothiadiazole mononucleotide prepared by treatment of the NAD analog with nucleotide pyrophosphatase. Both derivatives are potent inhibitors of inosine 5'-phosphate (IMP) dehydrogenase obtained from leukemia L1210 cells. The NAD analog is a pseudoir-reversible inhibitor of the enzyme, noncompetitive with either IMP or NAD. The aminothiadiazole mononucleotide has a K1 of about 0.1 muM, is competitive with IMP, and is uncompetitive with NAD: the inhibition appears to be reversible by Ackermann-Potter analysis. A metabolite of [5-14C]aminothiadiazole is formed in L1210 cells in vivo to a level of 0.3 nmole/10(9) cells. Retention volume of the metabolite on a high-pressure liquid chromatography system is the same as that of the aminothiadiazole mononucleotide prepared as described above. These results suggest that IMP dehydrogenase is the site of action for aminothiadiazole metabolites as was indicated by earlier observations. There is no evidence that the NAD analog is formed in vivo. Nicotinamide prevented formation of the mononucleotide in vivo. Therefore, since formation and cleavage of the NAD analog apparently are not the route to the thiadiazole nucleotide, some other pathway for the metabolism of nicotinamide may be involved such as the action of a phosphoribosyltransferase or the sequential action of a nucleoside phosphorylase and a nucleoside kinase.

The role of cholecystokinin in radiographic opacification of the gallbladder

Studies of the effect of cholecystokinin (CCK) on hepatic elimination of intravenously administered iopanoate and on gallbladder opacification were performed using nonoperated dogs with intact enterohepatic circulation and normal endogenous bile salt pool. Intravenous administration of CCK (3 units/kg) resulted in a 32% increase in apparent transport maximum (maximum rate of elimination) of iopanoate and earlier and enhanced gallbladder opacification. This increase in apparent transport maximum was abolished by cholecystectomy, indicating that the increase was a result of the release of bile salts from the gallbladder rather than a direct effect of the hormone on the hepatic elimination of iopanoate. The early gallbladder opacification and increased density of contrast material in the gallbladder were related to CCK-induced emptying of the gallbladder and subsequent filling with opacified bile.

Investigations of moving-slit radiography

The technique of moving-slit radiography for reduction of scattered radiation was investigated using a prototype moving-slit radiographic apparatus. Slit widths of 1-2 cm, when used in conjuction with an 8: 1 grid, were found to improve radiographic contrast by a factor of 2 in studies employing physical as well as anatomic phantoms. Use of the moving-slit technique at elevated kVp's was found to provide radiographic contrast as good as or better than that obtained in conventional low-kVp full-field techniques, but with a substantial reduction of patient exposure (factor of 2-4). Considerations in the design of an optimal multislit apparatus are discussed. Excessive tube loading is shown not to be a factor in such a system.

Anomalous biliary and pancreatic duct insertion into duodenal diverticula

Over a period of three years, anomalous insertion of the common bile duct and pancreatic duct into a duodenal diverticulum was observed in roughly 3% of all carefully performed T-tube cholangiograms. This would indicate that the lesion is relatively common and should be sought carefully. In this series, the association between the anomalous ductal insertion and biliary tract disease cannot be established, since the method of patient selection obviates any epidemiologic consideration. Of greatest significance is the fact that the anomaly can occur with several anatomic variations. Because of the multiple possible variations, careful radiographic evaluations of the biliary and pancreatic ductal system should be performed before any definitive surgery is directed toward a duodenal diverticulum.

Rupture of a splenic artery aneurysm into the pancreatic duct

A patient with hemorrhage into the pancreatic duct from a splenic artery aneurysm is presented. The angiographic, retrograde pancreatographic, and pathological findings are demonstrated. The diagnosis was established by demonstrating an enlarging aneurysm by serial angiograms. The location of the splenic artery aneurysm was confirmed by retrograde pancreatography before surgery. The distal pancreas containing the aneurysm was resected.

The effect of fractionated administration of locetamic acid (Cholebrine) on gallbladder visualization

Fractionated administration of iopanoic acid (Telepaque) has already been shown to result in superior visualization of the gallbladder. A similar study was undertaken to evaluate the effect of fractionation when iocetamic acid (Cholebrine) is employed. It was found that the gall bladder is opacified better if Cholebrine is given in a single dose.

An automated fluorescent excitation analysis system for medical applications

The use of stable tracers assayed by x-ray fluorescent excitation analysis has proven advantageous over other stable or radioisotopic techniques in a number of clinical and investigative situations. An automated fluorescent excitation analysis system for medical application has developed. Its design parameters and performance are described.

Effects of 2-amino-1,3,4-thiadiazole on ribonucleotide pools of leukemia L1210 cells

The effects of 2-amino-1,3,4-thiadiazole [aminothiadiazole (NSC 4728)] on purine and pyrimidine ribonucleotide pools of L1210 ascites cells in vivo are presented and discussed as they relate to the site of action. Within 1 hr after administration of the drug, the levels of guanosine triphosphate, guanosine diphosphate, adenosine triphosphate, and adenosine diphosphate were reduced, whereas those of inosine monophosphate (IMP) and uridine triphosphate were increased. The most pronounced effects were the lowering of guanine ribonucleotide pools and the elevation of IMP. Aminothiadiazole produced a marked inhibition (approximately 95%) of the incorporation of [8-14C]inosine into guanine nucleotides, whereas only a slight inhibition (approximately 20%) of incorporation into adenine nucleotides was observed. These results suggest that the thiadiazole (or a metabolite thereof) inhibits the conversion of IMP to guanosine monophosphate; this conclusion is reinforced by the observation that mycophenolic acid, a known inhibitor of this conversion, produced effects on ribonucleotide pools similar to those produced by aminothiadiazole. Aminothiadiazole did not inhibit IMP dehydrogenase isolated from L1210 cells. The effects of the thiadiazole on nucleotide pools were prevented by simultaneous administration of nicotinamide. Since nicotinamide is known to prevent or reverse the antileukemic activity of aminothiadiazole, it is probable that the inhibition of synthesis of guanosine monophosphate is related to the antileukemic action of this agent.

Purine nucleoside metabolism in the erythrocytes of patients with adenosine deaminase deficiency and severe combined immunodeficiency

Deficiency of erythrocytic and lymphocytic adenosine deaminase (ADA) occurs in some patients with severe combined immunodeficiency disease (SCID). SCID with ADA deficiency is inherited as an autosomal recessive trait. ADA is markedly reduced or undetectable in affected patients (homozygotes), and approximately one-half normal levels are found in individuals heterozygous for ADA deficiency. The metabolism of purine nucleosides was studied in erythrocytes from normal individuals, four ADA-deficiency patients, and two heterozygous individuals. ADA deficiency in intake erythrocytes was confirmed by a very sensitive ammonia-liberation technique. Erythrocytic ADA activity in three heterozygous individuals (0.07,0.08, and 0.14 mumolar units/ml of packed cells) was between that of the four normal controls (0.20-0.37 mumol/ml) and the ADA-deficient patients (no activity). In vitro, adenosine was incorporated principally into IMP in the heterozygous and normal individuals but into the adenosine nucleotides in the ADa-deficient patients. Coformycin (3-beta-D-ribofuranosyl-6,7,8-trihydroimidazo[4,5-4] [1,3] diazepin-8 (R)-ol), a potent inhibitor of ADA, made possible incorporation of adenosine nucleotides in the ADA-deficient patients...

Massive extra-enteric gastrointestinal bleeding: angiographic diagnosis

Two patients with massive gastrointestinal bleeding are reported. One bled from an aneurysm of a branch of the left hepatic artery, the blood reaching the bowel through communication with the biliary tree. The second had an aneurysm of a branch of the splenic artery which communicated with the pancreatic duct. This type of bleeding is intermittent and, consequently, actual extravasation of contrast media is not always seen. Therefore, if one sees an aneurysm of a visceral artery, even if it does not directly supply the enteric tract, one should consider the possibility that it is the origin of the hemorrhage. Pathogenesis, diagnostic modalities, and therapeutic implications are discussed.

Suture granulomas simulating tumors: a preventable postgastrectomy complication

Suture granulomas can occur after gastric surgery with nonabsorbable suture material. They are usually an asymptomatic, incidental finding on post-surgical x-ray studies, but have to be recognized because their radiological appearance may mimic gastric neoplasms and therefore may lead to unnecessary reoperations. Four cases of suture granulomas are presented, their diagnostic criteria outlined, and a plea is made for the use of a new completely absorbable suture material which could eliminate the occurrence of suture granulomas as well as the other known complications related to nonabsorable sutures, such as suture-line ulcers, abscesses, and adhesions.

In vivo measurement of hepatic iodine concentration using fluorescent excitation analysis

Hepatic iodine concentration was measured in the live dog by external use of fluorescent excitation analysis. The number of characteristic photons produced by interaction of exciting radiation from an americium-241 source with iodine within the tissue is proportional to the tissue iodine concentrations. A correction is made for absorption of radiation by the abdominal wall and other tissues lying between the volume of liver being assayed and the detector collimator. The technique is applicable to the in vivo measurement of iodine concentrations from 0.5 to 40 mg/g. Accuracy of the technique is approximately +/- 10%, which is within the range of variation in iodine concentration at various sites within the liver. Radiation dose is low, and radiolabeled tracer compounds need not be used.

Saturation kinetics of iopanoate in dogs with an intact enterohepatic circulation. Before and after phenobarbital induction

Capacity-limited elimination of sodium iopanoate and a reproducible apparent transport maximum (Tm) were demonstrated in nonoperated dogs having an intact enterohepatic circulation and normal endogenous bile salt pool. Using a multiple infusion technique, estimation of apparent Tm of iopanoate in the liver was possible without sampling either bile or urine. Values obtained for apparent Tm of iopanoate in dogs with normal bile salt pool were similar to those obtained in studies of dogs with chronic bile fistulas. Use of this technique in 4 dogs demonstrated that pretreatment with phenobarbital significantly increases apparent Tm of iopanoate.

Pseudocalculus of the common bile duct. A dynamic radiographic differentiation from true retained stone

Static T-tube cholangiographic evidence of distal common duct calculi may in fact be only "pseudocalculi," which might be elucidated by a dynamic fluoroscopic study. We have seen five such cases. X-ray evidence for this phenomenon is presented. Pertinent anatomy, physiology, and clinical considerations are discussed.

Mechanisms of action of 6-thioguanine, 6-mercaptopurine, and 8-azaguanine

The effects of 6-thioguanine on purine biosynthesis and cell viability have been examined in H.Ep. 2 cells grown in culture. Toxicity is not reversed by aminoimidazolecarboxamide, suggesting that inhibition of purine biosynthesis de novo is not the sole mechanism of toxicity. Also, 6-(methylmercapto)purine ribonucleoside, a potent inhibitor of purine biosynthesis de novo, produces more marked reductions in cellular pools of purines than does 6-thioguanine without killing cells. There is no apparent inhibition by 6-thioguanosine 5'-monophosphate of other enzymes leading to the synthesis of guanosine 5'-triphosphate as determined in whole cells by measurements of radioactive hypoxanthine or guanine incorporation. Inhibition of DNA synthesis by 1 mM thymidine protects cells from 6-mercaptopurine or 6-thioguanine but fails to protect cells from 8-azaguanine toxicity. On the other hand, inhibition of RNA synthesis by 6-azauridine plus deoxycytidine protects cells against 8-azaguanine but does not protect against 6-thioguanine or 6-mercaptopurine toxicity. In agreement with the in vitro data, arabinosylcytosine (a potent inhibitor of DNA synthesis) fails to protect mice against 8-azaguanine but has previously been shown to protect mice from 6-mercaptopurine or 6-thioguanine toxicity. The results support the hypotheses of others that incorporation into DNA (as 6-thioguanine nucleotide) is a mechanism of toxicity for these thiopurines, whereas 8-azaguanine is toxic due to its incorporation into RNA.

Growth inhibitory and arginase activities in liver and hepatoma extracts

The growth-inhibitory activity against H.Ep. No 2 cells observed in phosphate buffer extracts of rat liver appears to be due to the enzyme, arginase. This conclusion is based on the findings that (1) extracts of hepatomas containing lower levels of the enzyme also contain less inhibitory activity; (2) partial purification of the inhibitory factor results in a similar purification of the enzyme; (3) molecular weights of the enzyme and of the inhibitory factor are similar; and (4) various treatments alter the enzyme and inhibitory activities similarly.

The mechanism of action of 3-deazauridine in tumor cells sensitive and resistant to arabinosylcytosine

Deazauridine inhibited growth of tumor cells in culture and in culture and in vivo; this agent was significantly more effective against L1210/AraC than against the parent sensitive line. Inhibition of growth of tumor cells in culture was prevented by uridine and cytidine and was partially alleviated by deoxycytidine, but not by deoxyuridine or thymidine. DeazaUR inhibited nucleic acid synthesis but not protein synthesis in tumor cells in culture; deoxycytidine alleviated inhibition of nucleic acid synthesis. The labeling of pyrimidine ribonucleotides by 6-14C-orotic acid was inhbited by deazaUR. DeazaUR treatment of tumor cells in culture resulted in increased uptake of cytidine-3H into RNA, whereas uridine-3H uptake into RNA was inhibited. Labelling of DNA by uridine-3H/ and cytidine-H was inhibited by deazaUR. Pools of CMP, CDP, and CTP decreased markedly during deazaUR treatment of L1210 cells in culture and in vivo. These observations in growing cells pointed to deazaUR inhibition of the synthesis of cytidylic acid. Deazauridine 5'-triphosphate was found to be an inhibitor of the synthesis of CTP from UTP catalyzed by enzyme preparations from L1210 cells. This observation is in agreement with those of McPartland et al.19 that deazaUTP inhibited CTP synthetase purified from calf liver. Deazauridine treatment of L1210 cells in culture stimulated the uptake of deoxycytidine-3H into DNA while inhibiting the uptake of 3H-labeled deoxyuridine, thymidine, deoxyadenosine, and deoxyguanosine. Intracellular pools of dCTP were decreased by deazauridine treatment in L1210 cells in culture and in vivo. Deazauridine 5'-diphosphate inhibited the enzymatic reduction of pyrimidine ribonucleoside 5'-diphosphates to the corresponding deoxyribonucleotides. These results are consistent with the view that deazauridine, after its uptake and intracellular phosphorylation, strongly inhibits the formation of CTP. This is considered to be the primary metabolic effect of the analog. A secondary effect appears to be an inhibition of dCTP formation.

Saturation kinetics of iopanoate in the dog

Experiments were carried out in dogs with a modified Thomas cannula in the duodenum through which the common bile duct could be catheterized. Constant intravenous infusion of sodium iopanoate at different infusion rates greater than the apparent excretion maximum revealed linearity of the blood concentration with time above a threshold concentration. When the slopes of the blood curves were plotted against the known infusion rates, a straight line relationship was obtained. The X axis intercept of this straight line represents an apparent transport maximum. This value obtained from the X axis intercept matched closely with the observed excretion maximum determined from bile and urine collection. The slope of this same line equals the inverse of the volume of distribution of the drug. Although previous workers have failed to appreciate an apparent transport maximum for iopanoate, the current studies clearly demonstrate that iopanoate is excreted by a saturable mechanism. Using this technique the apparent transport maximum for iopanoate was evaluated at high and low rates of taurocholate replacement to evaluate the quantitative effect of bile salt on the apparent transport maximum. A five-fold increase in taurocholate replacement led to an average 40% increase in the apparent transport maximum of iopanoate without effecting its volume of distribution significantly.

Oropharyngeal dysphagia Manometric and cine esophagraphic findings

The manometric and cineradiographic features of 14 patients with oropharyngeal dysphagia are described. Failure of the upper-esophageal sphincter (UES) to relax completely and incoordination of UES relaxation with pharyngeal contraction were noted as was poor initiation of swallows and disorganization of pharyngeal contraction. The relative merits of cine esophagography and esophageal manometry in evaluating oropharyngeal dysphagia are assessed, and a functional classification for this disorder is proposed. Clinical improvement in 4 of 5 patients who underwent UES myotomy for severe intractable dysphagia did not always correlate with improvement in manometric and cine studies.