Tissue-specific splicing mutation in acute intermittent porphyria

An inherited deficiency of porphobilinogen deaminase [porphobilinogen ammonia-lyase (polymerizing), EC 4.3.1.8] in humans is responsible for the autosomal dominant disease acute intermittent porphyria. Different classes of mutations have been described at the protein level suggesting that this is a heterogeneous disease. It was previously demonstrated that porphobilinogen deaminase is encoded by two distinct mRNA species expressed in a tissue-specific manner. Analysis of the genomic sequences indicated that these two mRNAs are transcribed from two promoters and only differ in their first exon. The first mutation identified in the human porphobilinogen deaminase gene is a single-base substitution (G----A) in the canonical 5' splice donor site of intron 1. This mutation leads to a particular subtype of acute intermittent porphyria characterized by the restriction of the enzymatic defect to nonerythropoietic tissues. Hybridization analysis using oligonucleotide probes after in vitro amplification of genomic DNA offers another possibility of detecting asymptomatic carriers of the mutation in affected families.

Hemoperitoneum caused by rupture of a juvenile granulosa cell tumor in an equine neonate

A neonatal foal was examined because of apparent abdominal pain and distention, anemia, and hemoperitoneum. Exploratory laparotomy was performed, and a large spherical mass, which had ruptured, was found in the area of the left ovary. Left salpingo-oophorectomy was performed. The mass was determined to be a juvenile granulosa cell tumor.

The effects of human growth hormone administration in elderly adults with recent weight loss

The effects of human GH administration in elderly adults with recent weight loss were investigated in a metabolic ward study. Four patients were studied for 20 days. In addition to a constant caloric and nitrogen-sufficient diet, consisting of the recommended amounts of protein and energy plus 20%, the patients received GH in dosages of 25 and 50 micrograms/kg.day for two 4-day periods (days 5-8 and 13-16, respectively). Significant increases in nitrogen retention of 1.6 (114.2) and 1.4 g/day (100 mmol/day), respectively, occurred compared with that in the control periods. No difference was found between the two GH dosages, but the nitrogen-retaining effect of the higher dose appeared to last for several days after its administration was stopped. Plasma insulin-like growth factor I levels rose during both treatment periods. No important disturbances in carbohydrate metabolism occurred. Body weight increased 2.3 kg during each treatment period, probably due to water retention. We conclude that even during more than adequate nutritional intake, low GH doses cause considerable nitrogen retention in underweight adults.

Blood exchange and transfusion therapy for acute cholestasis in protoporphyria

Acute cholestasis is a rare complication of EPP with a high mortality rate despite extensive treatment with corticosteroids, cholestyramine, and antioxidants. A single survivor, reported in the literature, was treated with blood exchange transfusions. We treated two EPP patients with blood exchange and additional blood transfusions which resulted in full clinical and biochemical recovery from the cholestasis and accompanying hepatitis. Recurrences of the cholestasis and hepatitis could repeatedly be corrected by additional blood transfusions.

Serum procollagen III N-terminal peptide and laminin P1 fragment concentrations in alcoholic liver disease and primary biliary cirrhosis

Procollagen type III N-peptide (PIII NP) and laminin P1 fragment (LP1) have both been proposed as markers of liver fibrosis. In this study we evaluated the diagnostic application of both peptides in alcoholic liver disease and primary biliary cirrhosis. Serum concentrations of the peptides were measured by radioimmunoassay. PIII NP and LP1 levels appeared to be significantly raised in patients with alcoholic and primary biliary cirrhosis. Patients with alcohol abuse without cirrhosis had normal or slightly elevated PIII NP levels, but significantly raised LP1 levels. There was a strong correlation between PIII NP and LP1 concentrations.

Genetic analysis of structure and function in phage T4 tRNASer

We have determined the nucleotide sequences of 55 spontaneous mutations that inactivate a suppressor gene of phage T4 tRNASer. Most of the mutations caused substitutions or deletions of single nucleotides at 18 different positions in the tRNA. Two of three mutations that allowed the synthesis of mature tRNA had nucleotide substitutions at the junction of the dihydrouridine and anticodon stems, suggesting that this region of tRNASer is important for aminoacylation. The third mutation that synthesized tRNA had a nucleotide deletion in the anticodon loop, which presumably affected the translational capacity of the tRNA. We also sequenced 58 spontaneous reversion mutations derived from strains with the inactive suppressor genes. Some of these regenerated the initial tRNA sequence, while other generated a second-site mutation in the tRNA. These second-site mutations restored helical base-pairings to the tRNA that had been eliminated by the initial mutations. The new base-pairings involved G.C and A.U, and the A.C wobble pair at certain positions in the tRNA. This finding establishes the existence of A.C wobble pair in tRNA helices.

Host-parasite Relationship of Carrot Cultivars and Meloidogyne chitwoodi Races and M. hapla

Most of the 15 carrot cultivars tested were moderate to good hosts to Meloidogyne chitwoodi race 1, whereas all except Orlando Gold were nonhosts or poor hosts for M. chitwoodi race 2. All carrot cultivars were good hosts for M. hapla. The plant weights of the carrot cultivars Red Cored Chantenay and Orlando Gold infected with either race of M. chitwoodi were significantly less than uninoculated checks in pots. Under field microplot conditions, however, detrimental effects on quality were rarely observed. M. hapla was pathogenic to both cultivars in the greenhouse and the field. The tolerance level of Orlando Gold to M. hapla was lower than Red Cored Chantenay.

Avian mycobacteriosis in three horses

The clinical, bacteriologic and pathologic findings of three adult horses suffering from avian tuberculosis are presented. Chronic weight loss and hypoproteinemia were pertinent clinical abnormalities in all three horses. Gross pathologic lesions were characterized by chronic enterocolitis with mesenteric lymphadenopathy in two horses and hepatic granulomas in the third horse. The microscopic diagnoses were chronic, non-caseating granulomatous enterocolitis, and necrotizing, non-mineralizing granulomatous hepatitis, respectively. All three horses had granulomatous lymphadenitis of mesenteric lymph nodes with varying degrees of non-mineralizing, coagulation necrosis. Various serotypes of the Mycobacterium avium-intracellulare complex were isolated from selected tissues and feces.

Apparent undersensing due to oversensing of low amplitude pulses in a thoracic impedance-sensing, rate-responsive pacemaker

A case in which apparent undersensing was caused by detection of low amplitude impedance-measuring pulses emitted by a thoracic impedance-sensing rate-modulated pacemaker is described. The detection of these high frequency pulses was interpreted as "noise" by the pacemaker and led to asynchronous pacing in the interference reversion mode. Increasing the sensitivity failed to correct the problem. Decreasing the sensitivity eliminated oversensing of the low amplitude pulses and the apparent undersensing. Recognition of this phenomenon is important to prevent a misdiagnosis of undersensing.

Host Tests to Differentiate Meloidogyne chitwoodi Races 1 and 2 and M. hapla

The reproductive factor (R = final egg density at 55 days / 5,000, initial egg density) of Meloidogyne chitwoodi race 2 (alfalfa race) on 46 crop cultivars ranged from 0 to 130. The reproductive efficiency of M. chitwoodi race 1 (non-alfalfa race) and M. chitwoodi race 2 was compared on selected crop cultivars. The basic difference between the two races lay in their differential reproduction on Thor alfalfa and Red Cored Chantenay carrot. M. chitwoodi race 2 reproduced on alfalfa but not on carrot. Conversely, alfalfa was a poor host and carrots were suitable for M. chitwoodi race 1. Based on host responses to M. chitwoodi races and M. hapla, a new differential host test was proposed to distinguish the common root-knot nematode species of the Pacific Northwest.

Nisoldipine: kinetics and effects on blood pressure and heart rate in patients with liver cirrhosis after intravenous and oral administration

The pharmacokinetics and effects on blood pressure and heart rate of nisoldipine were studied in 8 patients with cirrhosis and in 8 age-matched healthy controls. On separate occasions each subject received nisoldipine by i.v. infusion (0.37 mg in 40 min) and as a tablet (5 mg for patients and 20 mg for control subjects). After i.v. nisoldipine, the elimination half-life was 9.7 h in control subjects and 16.6 h in the cirrhotics. The volume of distribution was 4.1 l/kg and 6.4 l/kg and the total systemic clearance was 847 ml/min and 494 ml/min, respectively. On oral nisoldipine, systemic availability was fourfold higher in patients with cirrhosis: 14.7% versus 3.7%. After i.v. administration of nisoldipine there was a brief decrease in systolic and diastolic blood pressure in both groups, whereas the heart rate increased. After 4 h a second effect peak appeared in the control subjects. After oral nisoldipine similar effect-time profiles were found, but effects lasted longer than after i.v. administration. Comparison of the maximal total plasma concentration of nisoldipine and the maximal effect in the two groups revealed that sensitivity to nisoldipine was not different in patients with cirrhosis. A reduction in the dose of nisoldipine is recommended when cirrhotics require oral nisoldipine in therapeutic practice.

ERCP diagnosis of tumors in the region of the head of the pancreas. Analysis of criteria and computer-aided diagnosis

During the period 1974-1983, 320 patients with pancreas carcinoma, papilla of Vater carcinoma, bile duct bifurcation carcinoma, or duodenal carcinoma were examined by ERCP. Using 30 ERCP criteria, a radiological diagnosis was made. A valid pathological diagnosis was available in 200 patients (62.5%). In 183 of the 200 patients (91.5%), the ERCP diagnosis and the pathological diagnosis were identical. We then performed an analysis using 52 ERCP criteria. In 192 of the 200 patients (96.0%), the ERCP diagnosis based on this reanalysis and the pathological diagnosis were identical. By discriminant analysis, 13 ERCP criteria with a maximal discriminatory value were selected in patients in whom all diagnostic structures (bile ducts, pancreatic duct, and duodenum) were visible. Using these 13 criteria selected by discriminant analysis, the diagnostic score was 98.9%. A computer program based on these 13 ERCP criteria was designed for use in practice. The diagnostic accuracy of this computer program was 98.4%. Finally we tested this computer program on 171 new patients who were seen in the period 1983-1986. In 143 of the 171 patients, a valid pathological diagnosis was available (83.6%). Comparing the ERCP diagnosis in all patients (even if not all structures were visible) with a valid pathological diagnosis, the prospective score of the computer program was 91.6%. Using this program it was possible to evaluate examinations in which not all structures were visible. When the ERCP diagnosis was uncertain, the doubt could be quantified.

Heteroduplex-induced mutagenesis in mammalian cells

We have shown previously that heteroduplexes containing single-stranded loops are repaired efficiently in monkey cells, but not always correctly: 2% of the repair products acquired mutations within a 350 base-pair target (Weiss, U. and Wilson, J.H., Proc. Natl. Acad. Sci. USA 87:1123-1126, 1987). The structures of the mutant genomes, which are described here, are consistent with an error-prone repair system. The spectrum of mutations includes about 25% point mutations and 75% rearrangements, which consist of deletions, duplications, and substitutions. The mutations are clustered in the vicinity of single-stranded loops in the original heteroduplex. The high frequency of mutation, their clustering, and the positions of rearrangement endpoints suggest that the mutations were generated during repair of the heteroduplexes.

Comparison of the production of eicosanoids by human and rat peritoneal macrophages and rat Kupffer cells

Human and rat peritoneal macrophages and rat Kupffer cells were labelled with [1-14C] arachidonic acid and stimulated with the calcium ionophore A23187. The metabolites formed were separated by high pressure liquid chromatography (HPLC). Human peritoneal macrophages formed especially leukotriene B4, 5-hydroxy-6,8,11,14 eicosatetraenoic acid and small amounts of leukotriene C4 and thromboxane B2, 12-hydroxy-5,8,10 heptadecatrienoic acid and 6-keto-prostaglandin F1 alpha, whereas rat peritoneal macrophages mainly produced cyclooxygenase products and in particular thromboxane B2 and 12-hydroxy-5,8,10 heptadecatrienoic acid. Rat Kupffer cells synthesized mainly cyclooxygenase products such as prostaglandin F2 alpha, prostaglandin D2 and prostaglandin E2. These results indicate that the profile of eicosanoids production by macrophages is dependent both on the species and on the tissue from which the macrophage is derived.

Prostanoid imbalance in experimental acute necrotizing pancreatitis in rats

In an investigation of the pathogenesis of acute necrotizing pancreatitis (ANP) the plasma levels of TXB2, 6-keto-PGF1 alpha, and PGE2 were measured in rats. After induction of ANP by injection of 5% sodium taurocholate into the pancreatic duct, a marked increase in TXB2 levels and a slight increase in 6-keto-PGF 1 alpha levels were found. PGE2 levels decreased. Mortality was 100% within 30 h. Pretreatment with chloroquine, a phospholipase A2 inhibitor, led to a inhibition of TXB2 production, whereas 6-keto-PGF1 alpha and PGE2 levels showed a surprising slight elevation in the first 6 h. Pretreatment with chloroquine decreased mortality by 30%. Pretreatment with FPL 55712, a leukotriene synthesis blocker, caused an increase in TXB2 and PGE2 levels, whereas the formation of 6-keto-PGF1 alpha remained unaltered. Two out of nine animals survived after pretreatment with FPL 55712. The results of the present study indicate that arachidonate end products are involved in ANP. The significance of the high TXB2 levels, decreased PGE2 levels, and only slightly elevated 6-keto-PGF1 alpha levels during ANP requires further investigation. The thromboxane A2 to prostacyclin ratio may be important.

Raised plasma thromboxane B2 levels in experimental acute necrotizing pancreatitis in rats. The effects of flunarizine, dazoxiben, and indomethacin

The possible role of thromboxane A2 (TXA2) in acute necrotizing pancreatitis (ANP) was investigated in rats. After ANP was induced by injecting sodium taurocholate (5% w/v) into the pancreatic duct, the thromboxane B2 (TXB2) levels in plasma increased significantly. The effects of indomethacin, a general blocker of prostaglandin synthesis, on survival time and on plasma TXB2 levels were compared with those of dazoxiben, a more specific blocker of TXA2 synthesis, and Flunarizine, a calcium entry blocker known to inhibit the effects of TXA2. In a test group without any treatment, all animals died within 30 h of ANP induction. Although TXB2 levels were lowered by the administration of indomethacin, dazoxiben, and Flunarizine, survival times were not significantly altered. Indomethacin pretreatment had no beneficial effect, whereas 30% and 40% of the animals survived for 36 h after treatment with Flunarizine and dazoxiben, respectively. The results of the present study indicate that inhibition of TXA2 synthesis alone does not dramatically alter survival time. However, a potential role for other arachidonate metabolites in ANP cannot be ruled out by this study.

Handling of iodothyronines by the liver and kidney in patients with chronic liver disease

Possible arterio-venous gradients of T4, T3, rT3 and 3,3'-diiodothyronine (3,3'-T2) across the liver and the kidneys were measured in 9 patients with varying degrees of liver failure undergoing diagnostic catheterization. Plasma iodothyronine levels were measured in peripheral, hepatic and renal veins before and at 10-min intervals until 60 min after iv injection of 400 micrograms of TRH. In 2 patients estimated hepatic plasma flow and effective renal plasma flow were determined as well. In these 2 patients, no significant differences between iodothyronine levels in arterial and peripheral venous plasma were found. T4 and T3 levels were not significantly different between peripheral, renal and hepatic veins. Hepatic vein rT3 and 3,3'-T2 concentrations were 10.7 +/- 8.3% (mean +/- SD, P less than 0.005) and 36 +/- 18% (P less than 0.001) lower than those in the peripheral vein (N = 9). Renal vein rT3 was just (6.2 +/- 7.5%, P less than 0.05) lower than rT3 in peripheral vein, whereas 3,3'-T2 was not different between the two veins. Estimates of hepatic and renal plasma flow were in agreement with values from the literature. On the basis of these data approximate hepatic clearance rates of 110 and 380 1/day for rT3 and 3,3'-T2 and a renal clearance rate of about 35 1/day for rT3 were calculated. Sixty min after TRH, plasma T3 was increased to 147 +/- 56% (P less than 0.05) and 3,3'-T2 in peripheral plasma was increased to 142 +/- 36% (P less than 0.025), whereas plasma T4 and rT3 did not change.(ABSTRACT TRUNCATED AT 250 WORDS)

Late results of mesocaval interposition shunting for bleeding oesophageal varices

Survival, encephalopathy and shunt patency were studied in 64 consecutive patients who underwent mesocaval shunting with a wide-calibre Dacron prosthesis. Half of the patients were operated as emergency cases. Operative blood loss in patients who had emergency procedures was significantly higher than during elective operations. Overall, 30-day mortality was 27 per cent. Survival was 61 per cent after 1 year and 39 per cent after 5 years. Serious encephalopathy requiring hospital admission occurred in 5 patients (11 per cent of patients surviving more than 1 month). Shunt patency was assessed by scintisplenoportography and ultrasonography. Cumulative shunt occlusion rate was 16 per cent after 1 year, 33 per cent after 5 years and 52 per cent after 8 years of follow-up. Out of 17 patients with an occluded shunt, 9 had persistent or recurrent bleeding, while 3 patients had recurrent bleeding despite a patent shunt. We conclude that the mesocaval Dacron interposition shunt should not be recommended as the procedure of first choice for portosystemic shunting.

Modification of DNA ends can decrease end joining relative to homologous recombination in mammalian cells

In animal cells, exogenous DNA recombines into random chromosomal sites much more frequently than it recombines into homologous sites. Free DNA ends are "recombinogenic" in both processes. To test the effects of specific ends on analogous extrachromosomal processes, we constructed a linear genome of simian virus 40 with terminal repeated sequences. After transfection into monkey cells, the model substrate can circularize by end joining (analogous to random integration) or by homologous recombination between its terminal repeats (analogous to targeted recombination). Since the two types of recombination are in competition with one another, the ratio of homologous-recombination to end-join products is a sensitive indicator of the differential effects of specific ends. Substrates with blunt ends, complementary sticky ends, or mismatched ends generated the same ratio of homologous-recombination to end-join products. However, addition of dideoxynucleotides to the 3' hydroxyls of the substrate decreased the frequency of end joining by a factor of 5-6 relative to homologous recombination. Thus, the frequency of end joining can be decreased relative to that of homologous recombination by modification of the ends of the input DNA. These results suggest an approach to altering the ratio of random to targeted integration in mammalian cells.

Physiologic regulation and tissue localization of renal erythropoietin messenger RNA

Although erythropoietin (Epo) is produced primarily by the kidneys in response to hypoxia, the precise cell type(s) and mechanisms by which these cells regulate production are poorly understood. In the experiments we report, the kinetics of renal Epo production in response to acute hypoxia and the intrarenal localization of cellular Epo synthesis were studied at the level of Epo mRNA. Erythropoietin mRNA expression was determined by Northern blot analysis of rat kidney RNAs using a probe derived from the mouse Epo gene. Renal Epo mRNA content increased as early as 1 hour after initiation of hypoxia and continued to accumulate during 4 hours of stimulation. Discontinuation of the hypoxic stimulus resulted in rapid decay of mRNA levels. Kidney and plasma Epo levels measured by radioimmunoassay paralleled, with respective lag times, the changes in renal Epo mRNA content, suggesting that Epo production in response to acute hypoxia represents de novo synthesis and is regulated by changes in Epo mRNA. Northern blot analysis of RNAs extracted from separated glomerular and tubular tissue fractions revealed Epo mRNA in the tubular fraction, whereas glomerular tissue did not contain Epo mRNA. Thus, the site of cellular Epo synthesis is located in the renal tubule or its interstitium and not in the glomerular tuft.

Disseminated Mycobacterium paratuberculosis infection in a cow

A cow with chronic diarrhea and weight loss caused by localization of Mycobacterium paratuberculosis in the intestinal tract (Johne's disease) had gross and microscopic changes indicative of a disseminated infection. A direct association between the remote lesions and the intestinal infection was shown by isolation of M paratuberculosis from renal tissue, detection of intracellular M paratuberculosis antigen(s), using an indirect immunoperoxidase method, and by the characteristic granulomatous nature of the lesions. This case illustrates the potential for extra-intestinal lesions in M paratuberculosis infection of cattle and should cause veterinarians to consider mycobacterial disease when confronted with multinodular lesions of the bovine kidney. The immunoperoxidase method was useful in determining the cause of the inflammatory lesion in which intact organisms were not evident.

Repair of single-stranded loops in heteroduplex DNA transfected into mammalian cells

Repair of heteroduplex DNA, generated between two interacting DNA molecules during homologous recombination, has been implicated as a contributing factor in the process of gene conversion. To assess patterns of heteroduplex repair in mammalian cells, we constructed 13 different heteroduplexes from simian virus 40 wild-type and deletion mutant DNAs. Each heteroduplex contained one or multiple single-stranded loops in the intron of the gene for large tumor antigen, which is not essential during lytic infection. After transfection into cultured monkey cells, cellular repair was evaluated by restriction analysis of the amplified viral progeny from 1123 individual plaques, each representing the clonal expansion of a single repair event. Single-stranded loops were corrected prior to replication with an overall efficiency of 90%. At the position of a loop, one of the two heteroduplex strands served as a template for accurate repair 98% of the time. Repair of single-stranded loops was biased nearly 2 to 1 in favor of the strand without the loop. The efficiency, accuracy, and strand bias of repair were unaffected by loop size within the tested range, which was 25-247 nucleotides. The excision tract associated with repair of single-stranded loops rarely exceeds 200-400 nucleotides in length.

Purification of porphobilinogen deaminase from human erythrocytes by fast protein liquid chromatography

A four-step procedure using fast protein liquid chromatography is described for the isolation of porphobilinogen deaminase from human erythrocytes. The specific activity of the porphobilinogen deaminase is increased about 13,000-fold, and the preparation is electrophoretically pure on SDS-polyacrylamide gel electrophoresis.

Nonhomologous recombination in mammalian cells: role for short sequence homologies in the joining reaction

Although DNA breakage and reunion in nonhomologous recombination are poorly understood, previous work suggests that short sequence homologies may play a role in the end-joining step in mammalian cells. To study the mechanism of end joining in more detail, we inserted a polylinker into the simian virus 40 T-antigen intron, cleaved the polylinker with different pairs of restriction enzymes, and transfected the resulting linear molecules into monkey cells. Analysis of 199 independent junctional sequences from seven constructs with different mismatched ends indicates that single-stranded extensions are relatively stable in monkey cells and that the terminal few nucleotides are critical for cell-mediated end joining. Furthermore, these studies define three mechanisms for end joining: single-strand, template-directed, and postrepair ligations. The latter two mechanisms depend on homologous pairing of one to six complementary bases to position the junction. All three mechanisms operate with similar overall efficiencies. The relevance of this work to targeted integration in mammalian cells is discussed.

A retrospective study of proliferative interstitial lung disease of horses in Florida

Proliferative and fibrosing interstitial lung disease was diagnosed in 20 horses submitted for necropsy between 1982 and 1985. Most of the horses were foals ranging from 3 days to 6 months in age. Six adult horses were affected. The macroscopic and microscopic characteristics of the lesions consisted of proliferative interstitial pneumonia and were similar to those of atypical interstitial pneumonia of ruminants. Based on morphologic features of the lesions, a toxic etiology is suspected for the induction of this naturally acquired primary equine lung disorder, but could not be specifically discovered by historical information.

Effects of caloric deprivation on thyroid hormone tissue uptake and generation of low-T3 syndrome

Changes in thyroid hormone metabolism in the low-3,5,3'-triiodothyronine (T3) syndrome cannot be fully explained in all conditions by a decrease in 5'-deiodinase activity. Recent observations showed that in rat hepatocytes iodothyronines are taken up by an active transport mechanism. To investigate whether regulation, i.e., inhibition of active transmembraneous transport for iodothyronines in humans may contribute to the generation of the low-T3 syndrome, tracer thyroxine (T4) and T3 kinetic studies were performed in 10 obese subjects before and after 7 days on a 240 kcal diet. Kinetics analyses were performed according to a three-pool model of distribution and metabolism for both T4 and T3. For T4 kinetics, during caloric deprivation serum total T4 and plasma pool did not change and production rate and metabolic clearance rate (MCR) were significantly lower. Despite a significantly higher serum free T4, the mass transfer rate to the rapidly equilibrating pool (REP) and the slowly equilibrating pool (SEP) diminished significantly, leading to smaller tissue pools. For T3 kinetics, both serum total T3, free T3, plasma pool, and production rate diminished significantly, while MCR remained unchanged. Mass transfer rates to the REP and the SEP were lowered by approximately 50%, leading to smaller tissue pools. These changes cannot be fully explained by a similar decrease of serum free T3 (only 25%), indicating a diminished transport efficiency for T3. In conclusion, during caloric restriction, transport of T4 and T3 into tissues is diminished, and this phenomenon is much more pronounced for T4 than for T3.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of deletions after initiation of simian virus 40 replication: influence of packaging limit of the capsid

Transfected DNA is frequently broken and rejoined in mammalian cells by recombination processes that depend on minimal nucleotide sequence homology. Although measurements of breakage and joining account reasonably well for the frequent formation of deletions during transfection, they are inadequate to explain the high frequency of deletion formation by simian virus 40 (SV40) genomes that are slightly larger than the packaging limit of the capsid. To investigate this anomaly, we constructed and transfected into CV-1 cells a series of modified SV40 genomes containing 136, 284, 460, and 656 extra base pairs in the intron of the gene encoding T antigen. These experiments indicate that the effective packaging limit of an SV40 capsid lies between 284 and 460 extra base pairs. Further analysis of these transfections suggests that molecules just above the effective packaging limit may be encapsidated and transmitted between cells at low efficiency, thereby allowing multiple rounds of replication and multiple opportunities to generate and package genomes that contain deletions. The junctional sequences in several such deletions were determined; they were similar to the junctions in deletions that were formed before replication began, suggesting that the enzymatic machinery responsible for both types of deletion may be similar.

Human peritoneal macrophages: clinical models of inflammation and potential targets of antiinflammatory drugs

Human peritoneal macrophages have been obtained from patients with renal disease undergoing chronic peritoneal dialysis, patients with ascites and at laparoscopy. These macrophages in general have both morphological and enzymatic characteristics of activated macrophages, as judged by criteria derived from animal experiments. Human peritoneal macrophages produce a variety of eicosanoids, including leukotriene B4 and leukotriene C4. These cells are suitable for studies on in vitro and in vivo effects of drugs, and for investigation of changes in macrophage activity occurring in human diseases.

Development of severe left ventricular outflow tract obstruction over the course of 14 years: an unusual natural history of hypertrophic obstructive cardiomyopathy

A patient with hypertrophic obstructive cardiomyopathy who when first seen had a normal physial examination, chest x-ray, and electrocardiogram, and no provokable gradient with isoproterenol at cardiac catheterization, was re-evaluated after 14 years. At the time of re-evaluation, she was found to have a typical systolic ejection murmur, cardiomegaly, left ventricular hypertrophy, a pseudoinfarction pattern on electrocardiography, and a significant subaortic gradient both by catheterization and by doppler. This case demonstrates that hypertrophic obstructive cardiomyopathy can be a progressive disease and that patients with this condition warrant careful follow-up. Echocardiography with doppler may provide an excellent noninvasive method of following these patients.

Chenodeoxycholic acid therapy in erythrohepatic protoporphyria

The short-term effect of chenodeoxycholic acid administration on the excretion of protoporphyrin was investigated in 5 patients suffering from erythrohepatic protoporphyria. Faeces were collected for 7 days, 10 ml of bile was sampled daily and blood was drawn every 2 to 3 days. Chenodeoxycholic acid was given in a dosage of 15 mg/kg/day from the 8th day. Collection of faeces, bile and blood was then continued for 10 more days. Protoporphyrin concentration was measured by high-pressure liquid chromatography and fluorometry. Following the administration of chenodeoxycholic acid the concentration of protoporphyrin in faeces and bile decreased significantly. In addition, all patients showed a significant decrease in erythrocyte protoporphyrin concentration. These results indicate that chenodeoxycholic acid therapy causes a marked decrease in the excretion of protoporphyrin in patients with erythrohepatic protoporphyria. The subsequent decrease in erythrocyte protoporphyrin suggests that chenodeoxycholic acid inhibits the production of protoporphyrin in the liver.

Production of leukotrienes and prostaglandins by human ascites cells

Ascites was collected from six patients with liver cirrhosis and the cells isolated. These cells, mainly macrophages, were labelled with 14C-arachidonic acid and stimulated with the calcium ionophore A23187. The metabolites formed were separated by HPLC. The main substances formed by the ascites cells were leukotriene B4, 5-hydroxy-6,8,11,14 eicosatetraenoic acid and leukotriene C4. Smaller amounts of thromboxane B2, 12-hydroxy-5,8,10 heptodecatrienoic acid and 6-keto-prostaglandin F1 alpha were isolated. Human peritoneal macrophages are therefore capable of producing leukotrienes and prostaglandins. Production of these substances might play a role in some of the complications of patients with liver cirrhosis and ascites.

Determination of haemoglobin in gastric aspirates

The haemoglobin content of gastric aspirates can be quantitated by conversion of non-fluorescent haem to fluorescent porphyrins by heating gastric aspirates with oxalic acid and ferrous sulphate. Recovery of haemoglobin added to gastric aspirates was 92 +/- 9%, variation coefficient, n = 52, day to day variation less than 8%. This method was used to calculate blood (haemoglobin) loss in 211 (24 hours) gastric aspirates obtained from 58 intensive care patients. Gastric blood loss was also measured by the 51Cr radiolabelled erythrocytes method in the same samples. There was a good linear correlation (r = 0.942, p less than 0.001) between the two methods. The fluorimetric method of quantitating haem is therefore suitable for detecting and measuring blood loss in gastric contents.

Intragastric prostaglandin E2 and the prevention of gastrointestinal hemorrhage in ICU patients

The effects of intragastric prostaglandin E2 (PGE2) on the occurrence of acute GI hemorrhage in intensive care patients were investigated in a prospective, double-blind, placebo-controlled study. Ninety patients with two or more risk factors (major surgery, multiple trauma, respiratory insufficiency, renal insufficiency, jaundice, hypotension, peritonitis, sepsis) were randomized for treatment with either PGE2 (0.5 mg) or placebo, administered every 4 h via a nasogastric tube. Blood loss in gastric aspirates was measured by 51Cr-erythrocyte labeling and a peroxidase test (orthotolidine). Of 57 patients who could be evaluated, 29 received PGE2 and 28 received placebo. Hemorrhage occurred in nine PGE2 patients and 13 placebo-treated patients, not a significant difference. The occurrence of hemorrhage was related to the number of risk factors, and GI hemorrhage was rarely the major factor determining mortality. Results of the orthotolidine test were not positively correlated with those of erythrocyte labeling, indicating that peroxidase tests should not be relied upon to detect blood in gastric aspirates.

Occipito-atlanto-axial malformation with atlanto-axial subluxation in an ataxic calf

Occipito-atlanto-axial malformation with atlanto-axial subluxation was diagnosed radiographically in a 4-day-old Holstein calf with a short neck, symmetric ataxia, and tetraparesis, indicative of a cervical spinal cord lesion. Necropsy confirmed the clinical diagnosis and revealed ribs on C-7, with partial fusion of C-7 and T-1. Histologic examination revealed focal degeneration of the spinal cord in the second cervical segment at the level of the atlanto-axial joint and extensive secondary neuronal fiber degeneration possibly caused by spinal cord trauma that occurred in utero.

Effect of body size and cage profile on the shear strength of bones of caged layers

The effects of body size and cage profile on the shear strength of bones from caged layers aged 72 weeks were studied. Bones tested included the radius, ulna, humerus, femur, and tibiotarsus. The ultimate shear force of the femur, tibia, and humerus all increased as body size increased (P less than 0.01). The wing bones of birds housed in high profile cages had higher shear breaking loads than birds housed in low profile cages. The ultimate shear stresses of the bones were not affected by body size or cage profile. The radius had the highest shear stress (29.2 MPa), followed in descending order by the ulna (19.1 MPa), tibiotarsus, humerus (11.4 MPa) and femur (11.3 MPa).

Mechanisms of nonhomologous recombination in mammalian cells

The primary mechanism of nonhomologous recombination in transfected DNA involves breakage followed by end joining. To probe the joining step in more detail, linear simian virus 40 genomes with mismatched ends were transfected into cultured monkey cells, and individual viable recombinants were analyzed. The transfected genomes carried mismatched ends as a result of cleavage with two restriction enzymes, the recognition sites of which are located in the intron of the gene encoding the T antigen. Because the T antigen gene was split by this cleavage, the transfected genomes were inert until activated by cell-mediated end joining. Clonal descendants of the original recombinants were isolated from 122 plaques and were grouped into four classes based on the electrophoretic mobility of the junction fragment. The structures of representative junctions were determined by nucleotide sequencing. The spectrum of nonhomologous junctions analyzed here along with a large number of previously reported junctions suggest that there are two mechanisms for the linkage of DNA molecules: (i) direct ligation of ends and (ii) repair synthesis primed by terminal homologies of a few nucleotides. A paired-priming model of nonhomologous recombination is discussed.

The validity of the SCL-90 in a sample of British men remanded to prison for psychiatric reports

The SCL-90 is a self-report inventory of psychopathology, which has not previously been validated in the UK. In the present study, the scale was found to correlate well with other measures of mental state, namely the Present State Examination (PSE) and the Comprehensive Psychopathological Rating Scale (CPRS). The scale was able to distinguish psychotic from non-psychotic patients on its paranoid ideation sub-scale, but not on its psychoticism one, nor any of its seven neurotic sub-scales. It is suggested that in research or population screening studies, this type of questionnaire should be supplemented with information relating to psychiatric history and motivation for treatment.