The interaction of proinsulin with the insulin-like growth factor-I receptor in human liver, muscle, and adipose tissue

Because of the sequence homology and tertiary structure similarities between proinsulin (PI) and insulin-like growth factor-I (IGF-I), it is possible that PI interacts with the IGF-I receptor with higher affinity than insulin. To test this hypothesis in man, we have partially purified IGF-I receptors from liver, muscle, and adipose tissue and studied their interaction with PI, insulin, IGF-I, and IGF-II. With some tissue to tissue variation, [125I]insulin binding was 4- to 8-fold greater than IGF-I binding. Unlabeled IGF-I at about 1 x 10(-9 M, IGF-II at about 1 x 10(-8) M, and insulin at about 1 x 10(-6) M displace 50% the binding of [125I]IGF-I to its receptor, whereas PI at 1 x 10(-6) M displaces less than 20% of the binding of [125I]IGF-I to its receptor. We conclude that in human liver, muscle, and adipose tissue, PI does not interact with the IGF-I receptor at a higher affinity than insulin, and the affinity of IGF-I receptors is several-fold lower than that of insulin receptors. It is, therefore, unlikely that if PI were to be administered to man any of its biological effects would be by interacting with the IGF-I receptor.

High-energy shock waves: in vitro effects

To date, there have been multiple studies on the effects of high-energy shock waves (HESW) on benign and malignant cells under in vitro conditions. The major problem in comparing and contrasting these studies has been the wide range of mechanical, biological, and analytical variables facing the investigator. However, if one takes the time to select out only those studies in which a wide range of experimental variables have been defined or controlled, then it becomes possible to begin to understand the effects of HESW on cells in vitro. With this in mind, the literature has been thoroughly reviewed. It would appear that HESW do cause cellular damage regardless of the cell's doubling time. The cell damage is likely due to the impact of cavitation and the attendant shear forces and jets that are produced by the shock waves as it passes through the cell suspension. The damage occurs both at the cell membrane and within the cell itself. With regard to the latter, it would appear that the mitochondria are most sensitive to HESW; however, damage also occurs within the nucleus and along the endoplasmic reticulum and in other cell organelles (eg, lyosomes). Applications of HESW to other clinical situations are currently being studied. One example of interest is the in vitro combination of chemotherapeutic agents and HESW to enhance the effect of a specific chemotherapeutic regimen on a given tumor cell line. Several investigators have noted a beneficial effect of this combination therapy in vitro; however, similar favorable results have not been obtained when the same or similar tumor system was studied in vivo.

Regulation of Rhizobium meliloti exo genes in free-living cells and in planta examined by using TnphoA fusions

The exo loci of Rhizobium meliloti are necessary for the production of an acidic exopolysaccharide, EPS I, that is needed for alfalfa nodule invasion by strain Rm1021. We have isolated and characterized alkaline phosphatase fusions made with TnphoA in several exo loci of R. meliloti and used these fusions to examine the subcellular localization of exo gene products and the regulation of exo genes in free-living cells and in planta. In the course of this work, we isolated a new exo locus, exoT. We have obtained evidence that several of the exo loci may encode membrane proteins. The activity of TnphoA fusions in several exo loci is increased two- to fivefold in the presence of the regulatory mutations exoR95 and exoS96. While examining the regulation of the exo gens by exoR95 and exoS96, we found that certain classes of exo mutations are lethal in an exoR95 or exoS96 background unless a plasmid complementing the exo mutation is present. This result has possible implications for the role of these exo loci in EPS I biosynthesis. We have developed a method for staining nodules specifically for the alkaline phosphatase activity present in the inducing bacteria and used this method to show that an exoF::TnphoA fusion is expressed mainly in the invasion zone of the nodule.

A cAMP-activated chloride channel in the plasma membrane of cultured human gastric cells (HGT-1)

Hydrochloric acid (HCl) secretion by gastric parietal cells involves an apical Cl- conductance, the properties of which have not been defined. In the present study, forskolin and histamine [agonists that increase intracellular cyclic adenosine monophosphate (cAMP)], and dibutyryl cAMP, activated channels in previously quiescent cell-attached membrane patches on cultured human gastric cells (HGT-1). In the cell-attached configuration (Cl- 149 mmol/l in bath and pipette), channels exhibited outward rectification, voltage dependence, inward current (-0.7 pA) at zero holding potential and a reversal potential of +24 mV, consistent with the presence of a Cl- conductive pathway. In excised inside-out patches, channels (i) exhibited degrees of outward rectification and voltage dependence that were comparable to those seen in cell-attached patches, (ii) demonstrated a -21 mV shift of their reversal potential when bath Cl- was decreased from 149 mmol/l to 53 mmol/l (calculated Cl-:cation permeability ratio 17:1), and (iii) were highly sensitive to the Cl- channel blocker diphenylamine-2-carboxylic acid (DPC, 10(-3) mol/l). This cAMP-activated Cl- channel bears many similarities to other Cl- channels within intestinal epithelia, and may represent the apical Cl- channel operating in HCl-secreting gastric parietal cells.

Acute phase proteins in neonatal rabbits: diminished C-reactive protein response

Acute phase protein response accompanies tissue injury, inflammation, or infection. During the acute phase, serum levels of C-reactive protein (CRP) can increase as much as 1,000-fold. We found that in response to an intramuscular injection of turpentine, neonatal rabbit CRP-specific RNA and serum CRP rose minimally. In contrast, adult serum levels of CRP increased 20-fold and mRNA for CRP in adults increased commensurately. However, during neonatal acute phase reactions, changes in the synthesis of the third component of complement (C3) and albumin were induced, implying a dysynchronous development of the response of various acute phase proteins.

Liver pathology in morbidly obese patients with and without diabetes

The contribution of obesity and/or diabetes to liver pathology in the morbidly obese patient is controversial. We studied the liver biopsies of 100 consecutive patients undergoing gastric bypass surgery for morbid obesity. Multiple morphologic parameters were analyzed and graded independently, without knowledge of the clinical history, liver function tests, and oral glucose tolerance results of the patients. Six percent of the entire group demonstrated no fat, 42% mild fat, 20% moderate fat, and 24% severe fatty metamorphosis of the liver. Twenty-three percent of the patients had central vein fibrosis, 23% sinusoidal fibrosis, 19% bridging fibrosis, and 4% cirrhosis. Thirty-six percent of the patients had some degree of steatohepatitis, 66% possessed so-called glycogen nuclei of hepatocytes, 6% had PAS-positive thickening of blood vessels in the portal tracts, and 1% had lipogranulomas. The degree of fatty metamorphosis and fibrosis was analyzed in three separate groups, categorized by the glycemic status of the patient: 46 patients with normal glucose tolerance (NGT), 23 patients with impaired glucose tolerance (IGT), and 31 patients with non-insulin-dependent diabetes mellitus (NIDDM). Increasing severity of fatty metamorphosis from the normoglycemic obese to the diabetic obese patients was found, which was statistically significant by chi 2 analysis. Four of the six patients showing no fatty metamorphosis were normoglycemic. Glycogen nuclei and PAS-positive blood vessels were significantly more prevalent in the diabetic obese than in the normal obese. In conclusion, the distribution of significant liver histopathology in the morbidly obese patient correlates in severity with the degree of impaired glycemic status.

Applicability of a threshold loading device for inspiratory muscle testing and training in patients with COPD

We evaluated application of a Pth device for testing inspiratory muscle endurance among patients with severe but stable COPD. Endurance time in five patients was reproducible. Magnitude of variability was +/- 1.26 minutes with a range of +/- 0.19 to +/- 2.28 minutes. Eleven inpatients completed inspiratory muscle training twice daily for four weeks in addition to their usual program of respiratory rehabilitation. The mean age of our experimental cohort was 65 years; FEV1, 33 +/- 12 percent predicted; and Dsb, 42 +/- 7 percent predicted. Baseline measurements showed no significant differences in pulmonary function, exercise tolerance, inspiratory muscle strength or inspiratory muscle endurance between control and study groups. Following training, the study group significantly improved inspiratory muscle endurance as evidenced by an increase in endurance time while breathing against the same absolute external Pth load used during baseline assessments. There were no associated changes in lung mechanics, muscle strength or exercise tolerance.

Genetic analysis of a cluster of genes required for synthesis of the calcofluor-binding exopolysaccharide of Rhizobium meliloti

Rhizobium meliloti produces an acidic, Calcofluor-binding exopolysaccharide which plays a role in nodulation of alfalfa plants by this bacterium. We constructed and mapped 102 transposon insertions in a 48-kilobase (kb) region previously shown to contain several exo genes. Mutations affecting production of the Calcofluor-binding exopolysaccharide were clustered in a 22-kb region and fell into 12 complementation groups. Strains carrying mutations in seven of the complementation groups (exoA, exoB, exoF, exoL, exoM, exoP, and exoQ) produced no Calcofluor-binding exopolysaccharide and induced non-nitrogen-fixing nodules on alfalfa. Mutants in an eighth complementation group, exoH (Leigh et al., Cell 51:579-587, 1987), produce an altered exopolysaccharide and also induce the formation of non-nitrogen-fixing nodules. Mutants in the remaining four complementation groups produced less Calcofluor-binding material than the wild type. Mutants carrying mutations in two of these complementation groups (exoK and exoN) formed apparently normal, nitrogen-fixing nodules, while mutants in the other two groups (exoG and exoJ) formed normal nodules less efficiently than the wild type.

Symbiotic loci of Rhizobium meliloti identified by random TnphoA mutagenesis

We have developed a system for using TnphoA (TnphoA is Tn5 IS50L::phoA), which generates fusions to alkaline phosphatase (C. Manoil and J. Beckwith, Proc. Natl. Acad. Sci. USA 82:8129-8133, 1985), in Rhizobium meliloti. Active fusions expressing alkaline phosphatase can arise only when this transposon inserts in genes encoding secreted or membrane-spanning proteins. By confining our screening to 1,250 TnphoA-generated mutants of R. meliloti that expressed alkaline phosphatase, we efficiently identified 25 symbiotically defective mutants, all of which formed ineffective (Fix-) nodules on alfalfa. Thirteen of the mutants were unable to synthesize an acidic exopolysaccharide (exo::TnphoA) that is required for nodule invasion. Twelve of the mutations created blocked at later stages of nodule development (fix::TnphoA) and were assigned to nine symbiotic loci. One of these appeared to be a previously undescribed locus located on the pRmeSU47a megaplasmid and to encode a membrane protein. Two others were located on the pRmeSU47b megaplasmid: one was a new locus which was induced by luteolin and encoded a membrane protein, and the other was dctA, the structural gene for dicarboxylic acid transport. The remaining six loci were located on the R. meliloti chromosome. One of these was inducible by luteolin and encoded a membrane protein which determined lipopolysaccharide structure. Three additional chromosomal loci also appeared to encode membrane proteins necessary for symbiosis. The remaining two chromosomal loci encoded periplasmic proteins required for symbiosis.

Assisting ventilation in respiratory failure by negative pressure ventilation and by rocking bed

The present study was undertaken to evaluate the effectiveness of acute ventilation by rocking bed (RB) and by negative-pressure ventilator (NPV) on arterial oxygenation and carbon dioxide tension in seven patients in whom respiratory failure (PaCO2 [+/- SD], 64 +/- 4 mm Hg; PaO2, 54 +/- 10 mm Hg) was consequent on nonobstructive ventilatory impairment. The increase in SaO2 (percent above baseline, 5 percent RB and 6 percent NPV) was similar for both methods, but a greater fall in PCO2 (percentage change in PCO2, 3 percent RB; 15 percent NPV; p less than 0.05) was observed during NPV. Diaphragmatic and accessory muscle electrical activity was markedly reduced during NPV but remained unchanged or increased on RB. Asynchronous breathing was frequently observed with RB but only rarely with NPV. These preliminary results suggest that effective mechanical ventilatory support could be achieved with either RB or NPV. However, their long-term effects as compared with those of positive-pressure ventilation remain to be explored.

2-Fluoro-oestradiol does not cause uterine refractoriness but inhibits oestradiol-induced implantation in rats

An intravenous injection of 2-fluoro-oestradiol simultaneously with an implantation-inducing dose of oestradiol reduced the number of implantation sites in delayed implanting hypophysectomized rats maintained with progesterone. Administration of 2-fluoro-oestradiol 1 h before or after oestradiol had no effect. Furthermore, injection of as much as 500 ng 2-fluoro-oestradiol 48 h before administration of oestradiol failed to have any effect upon implantation, i.e. failure to block implantation was correlated with failure to induce the uterine refractory state. These results suggest that conversion of primary oestrogens to catechol oestrogens could be important for implantation as well as for the induction of the oestrogen refractory state in the uterus.

Reversal of sleep-induced hypoventilation and chronic respiratory failure by nocturnal negative pressure ventilation in patients with restrictive ventilatory impairment

The efficacy of negative pressure ventilation (NPV) in alleviating sleep-induced reductions in alveolar ventilation and in producing long-term clinical benefits was studied in 5 patients (54 +/- 8 yr of age; mean +/- SD) with chronic respiratory failure secondary to restrictive ventilatory impairment (VC, 40 +/- 14% predicted; TLC, 72 +/- 18% predicted; FEV1/FVC, 89 +/- 15%). In control sleep studies, arterial O2 saturation decreased from 81 +/- 6% during wakefulness to 79 +/- 1% during non-REM sleep and to 67 +/- 3% during REM sleep, and transcutaneous PCO2 increased from 80 +/- 16 mm Hg during wakefulness and non-REM sleep to 87 +/- 16 mm Hg during REM sleep. Nocturnal NPV in a cuirass ventilator improved baseline ventilation during wakefulness and prevented deterioration of alveolar ventilation during sleep. Upper airway obstruction during sleep induced by NPV was successfully managed with either a tricyclic medication or nasal CPAP. After 8 wk of nocturnal NPV, all patients felt considerably better. Daytime resting arterial PCO2 decreased from 56 +/- 2 to 46 +/- 3 mm Hg (p less than 0.05) and PO2 increased from 51 +/- 9 to 70 +/- 10 mm Hg (NS). Four patients have continued NPV at home on a regular basis and have returned to full-time employment. We conclude that nocturnal NPV is an effective method of preventing sleep-induced reductions in alveolar ventilation and a practical method of long-term management of patients with nonobstructive chronic respiratory failure.

Teaching computation/shopping skills to mentally retarded adults

Three moderately/mildly retarded adults, ranging in age from 32 to 53 years, were trained in adaptive community skills. Behaviors identified for intervention (computational and shopping skills) were the same for all three clients. Assessment followed a multiple-baseline design across skills for each subject. The subjects were assessed in a classroom and in grocery stores in the community. Following baseline, treatment was provided that involved instructions, performance feedback, social reinforcement, in-vivo modeling, self-evaluation, and social and tangible reinforcement. Gains on both computational and shopping skills were stable or decreased during baseline, but rapid and dramatic improvements occurred soon after treatment began. Skills generalized to other stores, and these gains were maintained at a 2-month follow-up. Implications of the findings were discussed.

Immobilized Clostridium acetobutylicum P262 Mutants for Solvent Production

The production of acetone, butanol, and ethanol by two immobilized, sporulation-deficient (spo) Clostridium acetobutylicum P262 mutants which were held in the solventogenic phase was investigated. The spoA2 mutant, which was an early-sporulation mutant and did not form a forespore septum, produced higher solvent yields than did the spoB mutant which was a late-sporulation mutant and was blocked at a stage after forespore septum formation. The spoA2 mutant was also granulose and capsule negative. In a conventional batch fermentation, the wild-type strain produced 15.44 g of solvents per liter after 50 h at a productivity of 7.41 g of solvents per liter per day. The spoA2 mutant produced 15.42 g of solvents per liter at a productivity of 72.4 g of solvents per liter per day, with a retention time of 2.4 h in a continuous immobilized cell system employing a fluidized bed reactor. This represents a major advance, since the immobilization of wild-type cells showed similar increases in productivity but a ca. fivefold reduction in final product concentrations.

Pulmonary density distribution in experimental noncardiac canine pulmonary edema evaluated by computed transmission tomography

We evaluated the density distribution (anterior-posterior) of the right lung in 19 acutely anesthetized supine dogs using computed transmission tomography (CTT). Eleven dogs served as controls, and eight received 0.12 cc/kg of intravenously administered oleic acid. The latter were sequentially imaged over 1 hour. Nine of these dogs (three control and six oleic acid dogs) had wet weight/dry weight ratios of the corresponding anterior and posterior lung sections evaluated immediately upon completion of the scans. In the control animals, the posterior (dependent) lung was 25 +/- 8% (+/- S.D.) denser than the anterior lung, and did not differ if a second section of the lung was evaluated (1 cm cranial or caudal), or if the animal was imaged on a second day (n = 6). In the oleic acid dogs, the posterior portion of the lung was significantly denser 10 minutes after injection of oleic acid (P less than 0.05), and almost twice as dense 1 hour after initial injection. The density changes determined by CTT in the anterior and posterior lung zones correlated well with the increasing regional wet weight/dry weight relationships determined from the lung on postmortem exam (r = 0.90). We conclude that early subtle density changes in the posterior lung can be found in oleic acid injury pulmonary edema. This can be easily quantitated using CTT, and may prove useful in following physiologic and therapeutic interventions during leaky membrane acute pulmonary injury.

The role of urinary precipitates in the excretion of electrolytes and urate in the domestic fowl

1. In order to quantify losses of Na and K associated with precipitate fractions in semi-solid avian urines, Na, K, uric acid and urates (UA + U) and inulin were measured in plasma, in whole ureteral urine, and in urinary precipitates of hens. Ten animals were used, five fed a control commercial poultry meal (Diet A) and five maintained on a high protein, low-Na feed (Diet B). 2. In ureteral urines from hens on Diet A, dried precipitate accounted for 5.6% of the total whole urine weight, on the average. UA + U constituted about two-thirds of the precipitates' weight and 80% of the total excreted UA + U load of 97.4 mM. The average molar fractions, [Na]/[UA + U] and [K]/[UA + U], in precipitates were in the range 0.1-0.2; and the Na and K lost in these fractions were 12.8 mequiv and 9.6 mequiv, respectively, per 1 whole urine. These losses represent 9% and 23% of total Na and K excretion. 3. Diet B was used to accentuate potential cation loss in precipitates if obligatory binding of K and especially Na were to occur in precipitates. Urinary [UA + U] in whole urine rose to 146 mM of which 95% was found in precipitates. The average molar fraction [Na]/[UA + U], however, fell to 0.06 and that of [K]/[UA + U] to 0.08. Renal loss of Na was 8.5 mequiv and of K was 11.5 mequiv per 1 whole urine. 4. These experiments reveal that significant but minor fractions of excreted Na and K are associated with precipitates of avian urine, although the loss is insignificant compared to that reported in starlings (Braun, 1978). They further indicate that the Na/inulin clearance ratio, based on measurements in whole urine and plasma, adequately reflects fractional excretion which, on Diet A, was 1.8% of the filtered load and, on the Na-poor Diet B, less than 0.1%. These values place the Na-reabsorbing abilities of these birds easily within the range reported for ureotelic vertebrates and suggest that uricotelism does not impose a major renal salt loss in birds.

Renal acid excretion in the domestic fowl

1. In order to assess the role of uricotelism in net renal acid excretion, blood and ureteral urine samples were collected from five hens fed a commercial poultry feed (Diet A) and five hens fed a protein-rich, Na-poor feed (Diet B). All samples were analysed for pH, PCO2, ammonium, phosphate, uric acid and urates (UA + U) and inulin. 2. On Diet A, average pH in venous blood was 7.42, while urinary pH (pHu) ranged from 4.74 to 7.25. At average pHu (6.10), uric acid accounted for 52% of total acid excreted, H2PO4 for 20% and NH4 for 28%. Net acid excretion in ureteral urine was 345 muequiv h-1 kg body weight-1, or 5–10 times that observed in ureotelic vertebrates (amphibians and mammals). 3. The relative contributions of these urinary buffers to net renal acid excretion changed with pHu. Significant negative correlations exist between pHu and both total phosphate and ammonium excretion rates (P less than 0.001). Excretion rates of (UA + U) showed a positive correlation (P less than 0.05) with pHu. 4. Feeding on Diet B revealed the homeostatic power of the avian kidney. Blood pH and PCO2 were not changed relative to values in hens fed the control diet while striking increases in excretion rates of all urinary buffers (except HCO3) were observed. Average pHu fell to 5.12, and the average net renal acid excretion rate doubled.

Sporulation of Clostridium acetobutylicum P262 in a Defined Medium

A defined minimal sporulation medium for Clostridium acetobutylicum P262, which produces high levels of solvents, is described. The overall sporulation sequence was similar to that of other endospore-forming bacteria. However, we observed a presporulation stage, during which swollen phase-bright cells which contained large amounts of granulose formed. During sporulation, the initiation of spore coat formation occurred before the onset of cortex formation. Other Clostridium strains tested showed marked variations in ability to grow and sporulate in various minimal media.