A modified two primer approach to oligonucleotide-directed in vitro mutagenesis

Using oligonucleotide-directed mutagenesis, we are trying to define the features of the protein structure that are important for the DNA and c-AMP binding by CAP from E. coli, the enzymic activity and putative DNA binding of dihydrofolate reductase of L. casei, and the functionally important regions of the self-splicing RNA of the r-RNA intron of Tetrahymena thermophila. We have used a modification of the method described by Norris et al. [1]. A mutagenic primer and an M13 universal sequencing primer are annealed simultaneously to a template from an M13 clone containing the DNA to be mutagenised and, after DNA strand extension, the fragment is cut out and recloned into either M13 or plasmid vectors. We have analysed the effect on the frequency of mutation of: the temperature used for strand extension; the class of base change attempted; the host mismatch repair system. A recently developed system for phenotypic detection of mutations in the Tetrahymena intron aided in determining mutation frequencies.

Treatment of scaphoid nonunion by volar inlay distal radius bone graft

Volar inlay corticocancellous bone grafting is an accepted method of treatment for symptomatic nonunion of the carpal scaphoid. Performance of this procedure with a radial graft without styloidectomy yields results comparable to those obtained with iliac grafting. This permits the operation to be performed through a single incision. The elimination of the need for iliac dissection avoids morbidity associated with the iliac exposure.

The variability of fetal breathing movements in normal human fetuses at term

With the use of a B-scan phase-locked tracking system, 108 observations of fetal breathing were performed on 97 normal antenatal patients at term. One hundred thirty-three recorded segments of fetal breathing movements were obtained. Breath-to-breath variability was analyzed in 79 segments and expressed as a coefficient of variability. The mean coefficient of variability was 28.6% +/- 13.2%, and a histogram plot revealed a normal distribution. All fetuses had normal antepartum testing and all Apgar scores and neonatal courses were normal. The potential application of human fetal breathing variability as a test for fetal health is discussed.

The in vitro antibacterial activity of ceftriaxone in comparison with nine other antibiotics

The results of a large three centre co-ordinated study into the in vitro susceptibility of bacterial clinical pathogens showed no significant evidence of regional variation within the U.K. towards the 10 antibiotics examined. The newer cephalosporins were highly potent and superior to other antibiotics against the Enterobacteriaceae, with ceftriaxone and cefotaxime the most potent. Against Pseudomonas aeruginosa, gentamicin was the most active, followed by ceftazidime, piperacillin and ceftriaxone; cefotetan was the least active. Staphylococcus aureus and Staphylococcus albus were most susceptible to cefuroxime and gentamicin, though most were also susceptible to ceftriaxone, cefotaxime and cefoxitin. Streptococcus (Groups A and B), Streptococcus pneumoniae and Neisseria spp. were susceptible to most agents other than gentamicin, but ceftriaxone and cefotaxime were overall the most potent. Ceftriaxone was the most active agent against Haemophilus influenzae. The newer agents were variable and relatively poor against anaerobes and only amoxycillin and piperacillin were significantly active against Streptococcus faecalis. The overall resistance level to the third generation cephalosporins was low.

Nucleotide sequence of the dihydrofolate reductase gene of methotrexate-resistant Lactobacillus casei

The nucleotide sequence of the dihydrofolate reductase (DHFR) gene of a methotrexate-resistant strain of Lactobacillus casei, which is the source of DHFR for nuclear magnetic resonance (NMR) studies, has been determined. The derived amino acid sequence differs from that obtained by protein sequencing by the presence of aspartic acid instead of asparagine at position 8 and proline instead of leucine at position 90. The nucleotide sequences of 320-bp 5' and 335-bp 3' flanking regions of this gene have also been determined.

Can mixed venous blood be used to measure insulin action during the hyperinsulinemic clamp?

Mandatory use of arterialized venous blood for glucose measurement during insulin clamp studies can preclude its use in obese subjects. In order to assess the distortion produced by performing clamp studies with mixed venous blood, we have carried out the present study. Sixteen subjects (BMI range 21-53 kg/m2) whose glucose tolerance varied from normal to diabetic, had hyperinsulinemic clamps performed at plasma insulin concentrations approximately 250 microU/ml above basal, using arterialized venous (a.v.) blood for plasma glucose and insulin measurements. The test was repeated on the same subjects, but mixed venous (m.v.) blood was substituted for a.v. blood to determine plasma glucose and insulin concentrations. During the two studies, the mean (+/- SEM) steady state plasma glucose (a.v. = 110.6 +/- 8.8 mg/dl; m.v. = 111.3 +/- 9.8 mg/dl) and the mean incremental increases in insulin concentrations (a.v. = 263 +/- 20 microU/ml; m.v. = 273 +/- 21 microU/ml) were essentially identical. Furthermore, there was almost a perfect correlation between the individual values obtained for both SSPG (r = 0.97, p less than 0.001) and incremental insulin levels (r = 0.98, p less than 0.001) with the two methods. In addition, the amounts of glucose metabolized calculated from the two methods were very similar (a.v. = 4.96 +/- 0.67 mg/kg/min; m.v. = 5.25 +/- 0.76 mg/kg/min) and the two determinations of M were highly correlated (r = 0.97, p less than 0.001). Finally, the relative rank order of the M values obtained for the 16 subjects during the two studies were extremely comparable.(ABSTRACT TRUNCATED AT 250 WORDS)

Hereditary coproporphyria: incidence in a large English family

In a family inheriting the hereditary coproporphyria (HCP) gene, where 414 descendants have been traced through six generations and 135 members screened for faecal porphyrins, 27 subjects were found to have inherited the gene as well as the proband. Seven (six female and one male) in retrospect had probably previously suffered from a clinical attack of porphyria. Enzymological studies were carried out on 15 members and two unaffected parents and these results in general agreed with the faecal coproporphyrin readings. Symptomatic illness is low in HCP and is almost always precipitated by drugs known to have an adverse effect on the condition. If the gene is inherited, an attack can occur at any time between puberty and old age, such as in the proband at 84 years. We have detected abnormal faecal coproporphyrin levels in members of this pedigree as young as 12 years and as old as 87 years. Recommendations are given concerning the necessity of tracing relatives who may have inherited the gene and arranging for their biochemical screening and genetic counseling if indicated.

Thermolysin is a suitable protease for probing the surface of intact pea chloroplasts

Several proteases, i.e., pronase, a mixture of trypsin and chymotrypsin, and thermolysin were screened as potential surface probes of isolated intact pea (Pisum sativum var Laxton's Progress No. 9) chloroplasts. Of these, only thermolysin met the criteria of a suitable probe. Thermolysin destroyed outer envelope polypeptides, but did not affect inner envelope polypeptides, envelope permeability properties or such chloroplast activities as metabolite transport and O(2) evolution.

Renin-angiotensin-aldosterone system in nephrotic syndrome

Previous studies on the renin-angiotensin-aldosterone system and fluid volumes in patients with nephrotic syndrome have not considered the nature of the underlying renal lesion. We compared plasma renin concentration (PRC), plasma aldosterone (PA), and plasma volume in three groups of patients: five nephrotic patients with minimal change disease on renal biopsy, seven nephrotic patients with other renal histopathology, and a control group of eight patients investigated for glomerulonephritis with no past or present nephrosis. PRC and PA were significantly greater in nephrotic patients with minimal change disease than other renal histopathology (Supine PRC 42 +/- 7 microIU/mL compared with 14 +/- 4, P less than 0.01; ambulant PRC 56 +/- 7 microIU/mL compared with 29 +/- 10, P less than 0.05; supine PA 158 +/- 55 pg/mL compared with 53 +/- 13, P less than 0.05; and ambulant PA 167 +/- 57 pg/mL compared with 29 +/- 10, P less than 0.05. Plasma volume was similar in all three groups, contrary to predictions from the Starling capillary fluid exchange hypothesis. Nephrosis may be characterized by different pathophysiologic groups according to the underlying renal histopathology. High plasma renin and aldosterone levels may be markers for minimal change disease.

Mild splenic sequestration crises in sickle-hemoglobin C disease

Acute splenic sequestration crisis ( ASSC ), a common complication in homozygous sickle cell anemia, has been described infrequently in sickle-hemoglobin C (SC) disease in the absence of high altitude exposure. In this report, we describe three children with hemoglobin SC disease who developed episodes of ASSC that were milder than those generally described in sickle cell anemia. In one patient, an antecedent triggering event was not recognized. The other two children may have had a predisposing cause for massive intrasplenic sickling in that one had an associated mononucleosis syndrome and the other an episode of hypovolemic shock following severe epistaxis. ASSC may occur in patients with SC disease and does not necessarily require a hypoxic trigger associated with high altitudes.

S1 nuclease-sensitive sites in yeast DNA: an assay for radiation-induced base damage

DNA has been isolated from gamma-irradiated yeast cells and then treated with the enzyme S1 nuclease. This enzyme cleaves DNA specifically at sites where localized denaturation has occurred and can therefore be used as a lesion probe to identify regions in the DNA where base-pairing has been disrupted. By analysing the number of single strand breaks, double strand breaks and alkali-labile sites in the DNA before and after treatment with S1 nuclease, it has been possible to calculate the number of S1 nuclease-sensitive sites induced as a result of exposure to ionizing radiation. These sites were found to occur with a frequency about twice that of the double strand break and are thought to result from a primary ionization event in the DNA.

Prolonged pregnancy: surveillance of the fetus and the neonate and the course of labor and delivery

The perinatal events in 184 term control pregnancies and 129 prolonged pregnancies were prospectively compared. Fetal surveillance consisted of weekly biophysical profile testing. Thirty-two infants were dysmature, and 10 of these had advanced dysmaturity. The incidence of advanced dysmaturity rose quickly after 44 weeks. This group was at greater risk for fetal distress, lower Apgar scores, and emergency cesarean section. The combination of oligohydramnios, a suboptimal nonstress test, and a low profile score was highly predictive of a neonate with advanced dysmaturity. In the control pregnancies, the rate of induction of labor was 13.81% compared with 39.84% in the prolonged pregnancies. The induced labor group had a 51.32% cesarean section rate. Our approach to prolonged pregnancy consists of elective induction of labor when the cervix is favorable and biweekly profile testing when it is not; however, the high incidence of advanced dysmaturity after 44 weeks warrants delivery.

Mitoxantrone treatment in advanced breast cancer

Half of our patients presenting with breast cancer will eventually require cytotoxic chemotherapy. In searching for an effective drug with low toxicity, many new drugs have been investigated. Seventeen patients with advanced breast cancer were treated with mitoxantrone, an analogue of adriamycin. The response rate was 44% (CR 6% + PR 38%). Side effects were fewer than those normally anticipated for most cytotoxic chemotherapy in that only two patients suffered hair loss and three nausea and vomiting. There was, however, significant bone marrow depression with granulocytopenia and two patients died of septicaemia following treatment. Cardiac toxicity occurred in two patients: of these, both had prior treatment with adriamycin, and one had prior radiotherapy to the chest wall. Both of these patients died.

Lower respiratory tract infections in an acute geriatric male ward: a one-year prospective surveillance

A prospective study of 340 patients admitted to an acute geriatric male ward for a 12-month period was carried out to determine the aetiology and incidence of lower respiratory tract infection (LRTI) acquired either prior or after admission to the hospital. Over the year, 120 patients (35%) were found to have LRTI; a specific aetiology was found in 44 (37%) patients. The pathogens most frequently isolated were Haemophilus influenzae (11 patients), Streptococcus pneumoniae (9 patients) and influenza A (4 patients). A further 8 (7%) patients had antibody titres sufficiently raised to indicate a recent infection (influenza A6, Chlamydia psittaci 2). A marked difference in the aetiology between community- and hospital-acquired infection was demonstrated. Cross-infection was not found, although patients with influenza A infection were admitted to the ward. Mortality showed a high correlation with current and ex-smokers.

Effects of four-day fast on triglyceride mobilization in human adipocytes

To examine the effect of a four-day fast on neutral glyceride mobilization in human adipocytes, subcutaneous abdominal fat tissue was obtained from ten human volunteers after an overnight fast and then after four days of fasting. Plasma insulin concentration decreased from 31 +/- 5 microU/ml before the four-day fast to 9 +/- 1 microU/ml after the fast (P less than 0.05). Plasma free fatty acid concentration increased from 13.9 +/- 1.3 to 23.6 +/- 3.2 mg/dl (P less than 0.05). Mean average cell size was similar before and after the four-day fast. Basal lipolysis increased threefold (P less than 0.005) regardless of cell size after four days of fasting. In contrast, isoproterenol (2 microM) stimulated maximum lipolysis was not increased after a four-day fast. The concentrations of isoproterenol required for a half maximum stimulation in the presence of 50 (7 microU/ml) and 8000 pM (1150 microU/ml) insulin were lower after a four-day fast (P less than 0.05, P less than 0.03, respectively) and were uninfluenced by average cell size. Basal and maximum insulin-stimulated glucose transport were similar after a four-day fast. However, glucose incorporation into neutral glycerides was reduced by 50 percent (P less than 0.02) following a four-day fast. The reduction was uninfluenced by average cell size. The data indicate that abdominal adipocytes after a four-day fast are metabolically adapted towards increased neutral glyceride mobilization by reducing glucose incorporation into neutral glycerides, increasing sensitivity of lipolysis to isoproterenol, and increasing basal lipolysis.

Improvement in in vitro insulin action after one month of insulin therapy in obese noninsulin-dependent diabetics. Measurements of glucose transport and metabolism, insulin binding, and lipolysis in isolated adipocytes

It has been previously reported that maximum insulin-stimulated glucose transport and utilization were both decreased, while basal lipolysis was increased in adipocytes from obese subjects with noninsulin-dependent diabetes mellitus (NIDDM). To determine whether these values can be returned towards those obtained in equally obese subjects with normal glucose tolerance, these measures of adipocyte metabolism were quantified in 10 NIDDM subjects before and after control of hyperglycemia with insulin. The results demonstrate that maximum insulin-stimulated glucose transport (P less than 0.02) and glucose incorporation into triglyceride (P less than 0.01) and CO2 (P less than 0.05) (at 5.5 mM glucose) increased and basal lipolysis decreased (P less than 0.05) after 4 wk of insulin treatment. In contrast, glucose incorporation into lactate and other glycolytic metabolites (at 5.5 mM glucose), and sensitivity of glucose transport to insulin, did not improve with insulin therapy. The latter occurred despite an increase in insulin binding (P less than 0.01). Finally, the improvement in maximal insulin-stimulated glucose transport correlated with the fall in fasting hyperglycemia (r = 0.77, P less than 0.01). These findings demonstrate that several of the abnormalities of carbohydrate and lipid metabolism recently noted to be present in adipocytes from patients with NIDDM can be shown to significantly improve with insulin treatment.

Drug compliance not so bad, knowledge not so good--the elderly after hospital discharge

Thirty-five consecutive discharges from three admission wards were seen in hospital shortly before discharge and followed up 3-12 days after returning home. Various aspects of after-care were assessed, particularly in relation to drug compliance and understanding of treatment. Of the 30 on regular medication, 92% of those visited at home achieved over 95% compliance, despite the fact that most did not understand the purpose of their drug therapy. Much additional information was discovered, including the fact that many family doctors visited patients fairly soon when informed of discharge by telephone instead of by the normal posted discharge summary.

In vitro insulin resistance of human adipocytes isolated from subjects with noninsulin-dependent diabetes mellitus

To assess possible cellular mechanisms of in vitro resistance in noninsulin-dependent diabetes mellitus (NIDDM), maximum insulin-stimulated glucose transport and utilization and insulin binding were measured in adipocytes isolated from weight-matched normal glycemic subjects and patients with NIDDM. Glucose transport rate was determined by measuring the amount of [U-14C]-D-glucose taken up by incubating adipocytes at trace concentrations of glucose (300 nM), and glucose metabolism by estimating the amount of lactate, CO2, triglyceride, and total glucose carbons retained in the cells following incubating at 5.5 mM glucose. Insulin binding was measured at 50, 100, and 200 pM [mono125I-tyrosinyl A14]insulin. Both maximum insulin-stimulated glucose transport and utilization in adipocytes from diabetic subjects were 40% (P less than 0.01) and 32% (P less than 0.05) lower, respectively, than values obtained for subjects with normal glucose tolerance. In addition, the maximum capacity of glucose transport was correlated with the maximum capacity of glucose utilization (r = 0.81, P less than 0.001). Furthermore, fasting plasma glucose concentrations of diabetic subjects were negatively correlated with both maximum insulin-stimulated glucose transport (r = -0.56, P less than 0.05) and glucose utilization (r = -0.67, P less than 0.05). Since basal glucose transport in adipocytes from diabetic subjects was also 33% lower than in adipocytes from normal subjects, there was no change in the relative ability of insulin to stimulate glucose transport. However, there was a 64% decrease in the sensitivity of the glucose transport system to insulin (P less than 0.05), unrelated to concomitant changes in insulin binding. These results demonstrate that both maximal insulin-stimulated glucose transport and utilization, and the sensitivity of the glucose transport system to insulin, was decreased in adipocytes isolated from subjects with NIDDM. These in vitro defects were associated with impaired glucose metabolism in vivo, consistent with the view that the metabolic alterations observed at the cellular level may contribute to the in vivo insulin resistance of NIDDM.

Localization of human colorectal tumor xenografts in the nude mouse with the use of radiolabeled monoclonal antibody

For the evaluation of the clinical usefulness of monoclonal antibodies as diagnostic or therapeutic reagents, tumor localization must be clearly demonstrated in an experimental model. In this report, nude mice carrying two human tumor xenografts--a colon carcinoma (Colo 205) and a melanoma (Colo 239)--were given ip injections of radiolabeled monoclonal antibodies. Monoclonal antibody 250-30.6, which reacted specifically with the colon carcinoma but not with the melanoma, was labeled with 125I, while a second monoclonal antibody of similar immunoglobulin subclass, but unreactive with either cell type, was labeled with 131I. Both antibodies were injected simultaneously, and either the mice were scanned with a gamma camera or their tissues were removed and the localization of radiolabeled antibody was calculated with the use of localization index (LI)--the ratio of the tissue to blood distribution for each isotope. The studies showed that specific localization had occurred, there being a colon tumor LI of 6 at 2 days. Tumors of 150-300 mg (mean diameter, 6 mm) and with an LI as low as 1.5 could be successfully imaged after computer-assisted background subtraction. This study demonstrated that relatively small human tumor xenografts in the nude mouse can be specifically detected with the use of paired monoclonal antibodies, each labeled with a different isotope.

Attributions for undesirable life events, type A behavior and depression

This investigation examined attributions for life events and Type A behavior of 22 undergraduate women. It was expected that Type A students would make attributions associated with learned helplessness for undesirable life events. As hypothesized, Type A students engaged in more self-blame for important undesirable life events and also rated their desirable life events as less important than Type B students. Differences in attributional strategies of the two groups might mediate the relationship between Type A, helplessness, and heart disease.