Oral administration of insulin in winter-acclimatized carp (Cyprinus carpio) induces hepatic ultrastructural changes

1. The intestinal absorption of insulin in carps was assessed examining the transepithelial passage of ingested gold-labeled hormone by electron microscopy. Insulin transfer occurred mainly through the intercellular spaces between the enterocytes. 2. When reaching the lamina propria, the gold-labeled hormone gathered predominantly around the granules of the granular cells, and therefore can enter the circulatory system via the blood capillaries which are found in close contact with these cells. 3. Winter-acclimatized carp were also capable of internalizing the hormone when fed with insulin. 4. Furthermore, the absorbed hormone revealed full activity in regard to the observed changes in the ultrastructure of the liver cells of the treated cold-adapted fish. 5. The fish ingesting the hormone underwent the same type of hepatic ultrastructure reprogramming observed when winter-acclimatized carps are injected intraperitoneally with insulin, i.e. conversion to a phenotype corresponding to hepatocytes from summer-adapted carp. 6. The oral absorption of insulin by winter-acclimatized fish and its effect in reversing the cold-adaptive state might be useful for the fish culturing industry.

In vivo depletion of xenoreactive natural antibodies with an anti-mu monoclonal antibody

Hyperacute rejection of vascularized discordant xenografts, such as pig-to-primate kidney or heart xenotransplants, is thought to be mediated by xenoreactive natural antibodies (XNA) of the IgM isotype and the activation of the classic pathway of complement. Using the guinea pig-to-rat discordant xenograft model, we have developed a potential therapeutic protocol leading to long-term depletion of circulating IgM in adult animals. This protocol consists of the injection into adult LOU/C rats of an antirat IgM MAb (MARM-7) after splenectomy, plasma exchange, and the administration of an anti-B cell immunosuppressant, mycophenylate mofetil (RS61443). Splectomized plasma exchanged adult rats receiving RS61443 showed strongly decreased IgG and IgM serum concentrations for a relatively short period during which these isotypes remained nevertheless detectable by a sensitive ELISA technique. In contrast to IgM, IgG in serum returned, shortly after the end of this treatment, to normal concentrations. Splenectomy alone was able to significantly decrease, for a long period (more than 70 days), IgM but not IgG serum concentrations in these rats. During this treatment, IgM XNA concentration mirrored total IgM. The injection of MARM-7 MAb to adult LOU/C rats was able to deplete circulating IgM and IgM XNA for a period of several weeks during which IgM was undetectable by a sensitive ELISA technique. Depletion time was dose-dependent--the higher the dose of injected MARM-7, the longer the period for which IgM and IgM XNA remained undetectable. Moreover depletion of circulating IgM was correlated with the detection in the serum of these rats of noncomplexed, free MARM-7. Finally, MARM-7 administration was significantly more efficacious in rats that had decreased levels of circulating IgM after splenectomy, plasma exchange, and administration of RS61443. These experiments suggest that the anti-mu approach may allow depletion of IgM XNA for a sufficiently long period to test the hypothesis of "accommodation" in other xenograft models such as the pig-to-primate xenograft or even in ABO-incompatible allografts.

Complement deficiency states and meningococcal disease

Analysis of complement deficiency states has supported the role of complement in host defense and elucidated diseases associated with defective complement function. Although neisserial infection plays a prominent role in these deficiency states, examination of individuals with late complement component deficiency (LCCD) reveals a particular propensity for recurrent meningococcal disease and provides important clues to the role of complement in neisserial infections. In response to meningococcal disease, LCCD individuals produce significantly greater amounts of antilipooligosaccharide (LOS) antibody which can kill group B meningococcus in a complement-sufficient in vitro system. Further studies of antibody cross-reactivity to other meningococci has led to a clearer understanding of its epitopic specificity. Nevertheless, epidemiologic evidence is consistent with the relative absence of protective immunity in LCCD persons following an episode of infection and supported by quantitation of antibody to capsular polysaccharide. However, compared to anti-LOS antibodies, anticapsular antibodies can offer immune protection to LCCD individuals via complement-dependent opsonophagocytosis--the only form of complement-mediated killing available to these persons. Thus vaccination of LCCD persons with capsular antigens is considered an important means of protecting these high-risk individuals against meningococcal disease.

Suppression of synthesis of natural antibodies by mycophenolate mofetil (RS-61443). Its potential use in discordant xenografting

One of the major barriers to successful transplantation of immediately vascularized organs between discordant species is the presence of natural antibodies (NA) in the recipient. While natural antibodies can be depleted by plasmapheresis and/or organ absorption, they rapidly return to the circulation after such procedures. It will be desirable to suppress NA for longer periods of time. Since NA appear to be produced at least in part by CD5+ B cells, it was important to evaluate whether mycophenolate mofetil (RS-61443), a novel immunosuppressant that has been shown to suppress normally elicited antibody synthesis, would also be able to suppress NA. Adult rats were splenectomized, and 2 days later, 9 plasma exchanges, each of 4 ml, were performed. One group of rats received RS-61443 at 40 mg/kg/day (the dose described as efficacious for suppressing elicited antibodies in rats) starting immediately after the last exchange for 7 days, and then 20 mg/kg/day for an additional 7 days; no drug was given to the control group. NA levels were measured at various times by ELISA, using guinea pig platelets extracts as the target. Splenectomy alone led to a significant decrease from the control levels of NA; titers were further reduced by the plasma exchanges. In the absence of RS-61443, NA titers rose steadily, starting at 24 hr after the last plasma exchange. In contrast, administration of RS-61443 resulted in levels of NA on day 7 not significantly different from those after plasma exchange, reducing the dose of RS-61443 to the 20 mg/kg/day level during week 2 allowed the gradual return of NA. Administration of RS-61443 at the 40 mg/kg/day dose to rats after splenectomy alone led to a clear and significant further decrease in NA levels over the first week. It has been shown that RS-61443 can be administered for longer periods. The data presented suggest that use of this drug, perhaps with more conventional agents, may allow suppression of NA for a significant period after transplantation.

Vaccination with SPf66, a chemically synthesised vaccine, against Plasmodium falciparum malaria in Colombia

Preclinical and clinical studies have established the safety and immunogenicity of the chemically synthesised SPf66 malaria vaccine. The present study is a phase III randomised, double-blind, placebo-controlled, efficacy trial completed in La Tola, Colombia. 1548 volunteers over one year of age received three doses of either the vaccine (n = 738) or placebo (n = 810). Active and passive case detection methods were used to document clinical episodes of malaria among the study population. The follow-up period began one month after the third dose and lasted for one year. 168 and 297 episodes of Plasmodium falciparum malaria were documented in the SPf66 group and the placebo group, respectively; this corresponds to a crude protective efficacy of 38.8%. Incidence rates for first or only P falciparum malarial episodes were 22.3% per annum among the vaccinee group and 33.5% among the placebo group (RR = 1.5; 95% Cl 1.23, 1.84). Therefore, the protective efficacy of SPf66 against first or only episodes was 33.6% (95% Cl 18.8, 45.7), being highest in children aged 1-4 years (77%) and adults older than 45 years (67%). The estimated protective efficacy against second episodes was 50.5% (95% Cl 12.9-71.9). Our study shows that the chemically synthesised SPf66 malaria vaccine is safe, immunogenic, and protective against P falciparum malaria in semi-immune populations subject to natural challenge.

Evidence that 15-deoxyspergualin inhibits natural antibody production but fails to prevent hyperacute rejection in a discordant xenograft model

Preventing hyperacute rejection (HAR) is a difficult and unsolved problem in xenotransplantation. This may be due, in part, to a lack of therapies that can suppress production of natural antibodies (NA), which are thought to be critical mediators of HAR. This study examined the effect of 15-deoxyspergualin (DSPG) and splenectomy (Spx) on NA production and return of NA after plasma exchange (PE) in a discordant species combination (strain 2 guinea pig to Lewis rat). A dose of 5 mg/kg/day DSPG + Spx significantly reduced Lewis rat anti-guinea pig NA titer after one week of therapy. Antibody titer was not significantly reduced in rats treated with splenectomy alone. PE alone acutely depleted NA titers; however, complete rebound was seen in 48 hr. When PE was performed in rats treated with DSPG + Spx, an additional significant NA reduction occurred; no rebound 24-48 hr after PE was seen. Except for a 20% reduction in body weight, no serious complications occurred in DSPG + Spx recipients. Despite a profound NA titer reduction, treatment with DSPG, Spx, and PE did not prolong guinea pig cardiac xenograft survival in a clinically significant fashion. Immunopathological study of rejected cardiac xenografts revealed no antibody deposition but persistent complement deposition on vascular endothelium. We conclude that DSPG + Spx effectively inhibits synthesis of rat anti-guinea pig NA, that further NA titer reduction can be achieved with the addition of PE, and that DSPG + Spx prevents post-PE antibody rebound. We also conclude that the limited prolongation in cardiac xenograft survival achieved, despite marked suppression of NA, supports a complement-mediated mechanism of HAR in our animal model.

Production of species-specific murine monoclonal antibodies against Cryptococcus neoformans which recognize a noncapsular exoantigen

Three monoclonal antibodies (MAbs), designated 7C5, 7C9, and 5G8, against a cytoplasmic antigen of Cryptococcus neoformans were produced. MAbs 7C5 and 7C9 recognize culture filtrate antigen (exoantigen) of both encapsulated and nonencapsulated isolates of this pathogen, which suggests that they do not recognize capsular polysaccharide material. This is supported by immunofluorescence data which show reactivity of all 3 MAbs to cytoplasm and cell membranes only. MAb 7C9 also recognized C. neoformans var. gattii antigens but no other fungal pathogens tested in an enzyme-linked immunosorbent assay, while 7C5 and 5G8 recognized antigens of the cross-reactive pathogen Trichosporon beigelii but did not recognize either C. neoformans var. gattii isolates or any other fungal antigens. By Western blot (immunoblot), 7C9 detected antigen at 110 to 120, 65 to 70, 45 to 50, and 36 to 38 kDa; in addition to the latter band, the other two MAbs recognized a band at approximately 30 kDa. All three MAbs were of the immunoglobulin G1 subclass. The two MAbs which are capable of reacting with noncapsular culture supernatant antigen have possible uses in serodiagnosis, particularly in AIDS patients infected with C. neoformans, since in this group the present latex agglutination test has some limitations.

Na+/Na+ exchange and Na+/H+ antiport in rabbit erythrocytes: two distinct transport systems

Rabbit erythrocytes are well known for possessing highly active Na+/Na- and Na+/H+ countertransport systems. Since these two transport systems share many similar properties, the possibility exists that they represent different transport modes of a single transport molecule. Therefore, we evaluated this hypothesis by measuring Na+ transport through these exchangers in acid-loaded cells. In addition, selective inhibitors of these transport systems such as ethylisopropyl-amiloride (EIPA) and N-ethymaleimide (NEM) were used. Na+/Na+ exchange activity, determined as the Na+o-dependent 22Na efflux or Na+i-induced 22Na entry was completely abolished by NEM. This inhibitor, however, did not affect the H+i-induced Na+ entry sensitive to amiloride (Na+/H+ exchange activity). Similarly, EIPA, a strong inhibitor of the Na+/H+ exchanger, did not inhibit Na+/Na- countertransport, suggesting the independent nature of both transport systems. The possibility that the NEM-sensitive Na+/Na+ exchanger could be involved in Na+/H+ countertransport was suggested by studies in which the net Na+ transport sensitive to NEM was determined. As expected, net Na+ transport through this transport system was zero at different [Na+]i/[Na+]o ratios when intracellular pH was 7.2. However, at pHi = 6.1, net Na+ influx occurred when [Na+]i was lower than 39 mM. Valinomycin, which at low [K+]o clamps the membrane potential close to the K+ equilibrium potential, did not affect the net NEM-sensitive Na+ entry but markedly stimulated the EIPA- and NEM-resistant Na+ uptake. This suggest that the net Na+ entry through the NEM-sensitive pathway at low pHi, is mediated by electroneutral process possibly involving Na+/H+ exchange. In contrast, the EIPA-sensitive Na+/H+ exchanger is not involved in Na+/Na+ countertransport, because Na+ transport through this mechanism is not affected by an increase in cell Na+ from 0.4 to 39 mM.(ABSTRACT TRUNCATED AT 250 WORDS)

Murine monoclonal antibodies recognizing a non-capsular antigen that distinguishes between Cryptococcus neoformans var. neoformans and C. neoformans var. gattii

A panel of 4 monoclonal antibodies (mabs) of the IgG1 subclass have been made against a cytoplasmic antigen of Cryptococcus neoformans. Mab 4E2 recognized isolates of C. neoformans var. gatti by enzyme-linked immunosorbent assay (ELISA), whilst the other antibodies did not recognize these antigens. By Western blot 4E2 recognized determinants at 110-125, 65-70, 45-50 and 36-38 kDa. Mabs 9E6, 7C7 and 5D9 recognized bands at 36-38 and approximately 30 kDa. All 4 mabs (4E2, 9E6, 7C7 and 5D9) recognized both non-encapsulated and encapsulated isolates of C. neoformans var. neoformans by ELISA, and in addition showed reactivity to only the cytoplasm and cell membrane of yeasts by immunofluorescence. Mab 7C7 recognized antigens of the closely related fungus Trichosporon beigelii by ELISA but did not recognize any other fungal antigens. The other 3 mabs showed no recognition of T. beigelii or any other fungal pathogens tested.

Leprosy in Puerto Rico: a decade later

A study to evaluate the changes in the incidence and prevalence of leprosy in Puerto Rico was done to include the years 1981-1989. During this period, 75 new cases were diagnosed with an average of 8.3 cases per year. The yearly incidence was 1.9 cases per million which is significantly lower to the 4.6 per million in the previous study. At the present moment 182 cases are been followed at the Tropical Diseases Clinic of the University of Puerto Rico School of Medicine with a prevalence of 5.4 per 100,000 inhabitants. It is important to notice that 16 percent of the patients at the clinic were foreigners, a significant increase from a previous study. The decrease in the incidence of leprosy may be due to advances in the treatment of the disease and the new approach to integrate the patient into the community.

Preparation of monoclonal antibodies that differentiate between Histoplasma capsulatum variant capsulatum and H. capsulatum variant duboisii

The immunosuppressive drug cyclophosphamide was used to facilitate the production of monoclonal antibodies (Mabs) which differentiated between the yeast phase of the two variants of the dimorphic fungus Histoplasma capsulatum by both enzyme-linked immunosorbent assay and Western blot. Two Mabs are described, identifying epitopes on a 70-75 kDa molecule, which are specific to H. capsulatum var. capsulatum and which do not identify epitopes of H. capsulatum var. duboisii. These Mabs have potential use in the epidemiology and serodiagnosis of histoplasmosis in areas where both classical and African forms of the disease occur.

Vasotocin genes of the teleost fish Catostomus commersoni: gene structure, exon-intron boundary, and hormone precursor organization

cDNA clones encoding two members of the vasotocin hormone precursor gene family have been isolated from the white sucker Catostomus commersoni. The hormone is encoded by at least two distinct genes, both of which are expressed, as indicated by Northern blot analysis. Genomic DNA amplified by the polymerase chain reaction has been used to define exon-intron boundaries. Both vasotocin genes contain introns in positions corresponding to those found in the gene of their mammalian counterpart vasopressin. The predicted vasotocin precursors show a surprising degree of sequence divergence, amounting to 45% at the amino acid level, of which only approximately half can be accounted for by conservative amino acid changes. The precursors include a hormone moiety followed by a putative neurophysin sequence that is longer at the C-terminus by a tract of some 30 amino acids by comparison to their mammalian counterpart. Each of these sequences contains a leucine-rich core segment resembling that found in copeptin, a glycopeptide moiety present in mammalian vasopressin precursors.

A murine monoclonal antibody exhibiting high species specificity for Histoplasma capsulatum var. capsulatum

A monoclonal antibody (mAb) exhibiting a high degree of species specificity for the yeast phase of the dimorphic fungus Histoplasma capsulatum was produced by a modification of the standard mAb production protocol. The technique for generating mAbs involved the use of the immunosuppressive drug cyclophosphamide to diminish the response in mice to immunodominant cross-reactive epitopes. This mAb exhibited clear specificity and did not react by ELISA with the closely related genera Blastomyces, Paracoccidioides and Sporothrix. In Western blots it recognized a linear determinant on a 70-75 kDa molecule in H. capsulatum antigen, with an extremely faint reactivity to antigens of identical molecular mass derived from Sporothrix and Paracoccidioides, and no reactivity against Blastomyces antigen.

Two isotocin genes are present in the white sucker Catostomus commersoni both lacking introns in their protein coding regions

Two genes each encoding a distinct precursor protein to the hormone isotocin and a neurophysin-related protein are present in the teleost fish Catostomus commersoni. These precursors are referred to as isotocin 1 and 2. As shown by the polymerase chain reaction technique, both genes lack introns in their protein-coding sequences. Both genes are transcribed giving rise to mRNAs of 920 (isotocin 1) and 1020 (isotocin 2) bases, respectively. Based on the nucleotide sequences, the predicted isotocin precursors contain, besides the hormone moiety, a neurophysin-like protein that, in contrast to its mammalian counterpart, is extended at its C-terminus by a peptide which includes a leucine-rich core segment. This segment shows similarities to the copeptin of the mammalian vasopressin precursor that is known to possess prolactin-releasing activity. The data imply that the mammalian copeptin sequence was initially part of a larger ancestral neurophysin molecule.

Vasotocin and isotocin precursors from the white sucker, Catostomus commersoni: cloning and sequence analysis of the cDNAs

The nucleotide sequences of cloned cDNAs encoding the precursors for vasotocin and isotocin have been elucidated by analyzing a lambda gt11 library constructed from poly(A)+ RNA from the hypothalamic region of the teleost fish Catostomus commersoni. Screening of the library was carried out with synthetic oligonucleotide probes deduced from the amino acid sequences of the nonapeptides vasotocin and isotocin. The cDNA nucleotide sequences predict isotocin and vasotocin prohormone precursors each consisting of a signal peptide, a hormone moiety, and a neurophysin-like molecule. However, in comparison to their mammalian counterparts, both fish neurophysins are extended at their C termini by an approximately 30 amino acid sequence with a leucine-rich core segment. These extensions show striking similarities with the glycopeptide moiety (the so-called copeptin) present in mammalian vasopressin precursors, except that they lack the consensus sequence for N-glycosylation. These data suggest that mammalian copeptin is derived from the C terminus of an ancestral neurophysin.

The major component of the rat sperm fibrous sheath is a phosphoprotein

The fibrous sheath from rat epididymal sperm was isolated by sequential extraction, first with Triton X-100 and dithiothreitol, and then with 6 M urea and dithiothreitol. The latter extraction procedure solubilized most of the sperm components, leaving the head and the fibrous sheath as the only intact structures. This material was purified by sucrose gradient centrifugation. Electron microscopy confirmed the purity of the isolated material and revealed the characteristic structural features of the fibrous sheath. Polyacrylamide gel electrophoresis (in the presence of sodium dodecyl sulfate) of the fibrillar material, showed a complex polypeptide composition. The polypeptides with molecular weights of 80,000, 24,000, and 11,500 accounted for about 65% of the total protein of the fibrous sheath. Peptide map analyses indicated that the components of molecular weights of 80,000 and 24,000 are unrelated to the polypeptides of similar size of the outer dense fibers. On the other hand, it appears that the fibrous sheath and the outer dense fibers share the polypeptide of 11,500 daltons. The component of 80,000 daltons contains on the average about 3 mol of phosphoserine per mol of polypeptide, indicating that the most abundant polypeptide of the fibrous sheath is a phosphoprotein.

Intracellular distribution of poly(ADP-ribose) synthetase in rat spermatogenic cells

The highest activity of poly(ADP-ribose) synthetase was found in the testis among several rat tissues tested. Subcellular fractionation of the testis demonstrated that the synthetase was localized primarily in the nucleus and partially in the microsomal-ribosomal fraction. This result was confirmed by immunocytochemical staining with the enzyme-specific antibody. The synthetase was localized in the nuclei of interstitial cells, Sertoli cells, spermatogonia, and spermatocytes. In addition, round spermatids showed a granular staining in the cytoplasm, which was comparable in intensity with that in the nucleus. The cytoplasmic synthetase had a molecular weight of 115,000 and synthesized oligomers of ADP-ribose on itself (automodification). The synthetase activity in the isolated cytoplasmic fraction was stimulated about threefold by the addition of DNA and depressed by treatment with DNase I, suggesting the presence of endogenous activator DNA. A candidate DNA for such an activator was isolated from the microsomal-ribosomal fraction, and identified tentatively as mitochondrial DNA on the basis of its size and restriction fragment patterns.

Presence of RNA in the sperm nucleus

The RNase-colloidal gold procedure for the ultrastructural localization of RNA was used for rat testis. Along with other structures, it was found that the testicular sperm nucleus was well stained. Similar labelling was observed in the nucleus of rat epididymal sperm and human sperm. The RNA was extracted from sperm and analyzed by electrophoresis on 10% polyacrylamide gel and 7 M urea. The electrophoretic profile revealed a complex set of bands ranging in size from tRNA to high molecular weight components. On the average, a content of about 0.1 pg of RNA per rat or human sperm was found.

The effect of mild hypoxemia maintained for twenty-four hours on maternal and fetal glucose, lactate, cortisol, and arginine vasopressin in pregnant sheep at 122 to 139 days' gestation

The effects of prolonged mild hypoxemia on the fetus have received little attention. We investigated the response to a decrease in fetal arterial Po2 of 5 mm Hg or less sustained for a period of 24 hours in the chronically instrumented fetal lamb. Hypoxemia was induced by an infusion of nitrogen via the maternal trachea for 24 hours in 13 pregnant sheep at 122 to 139 days' gestation. Two control periods of air infusion via the maternal trachea for 24 hours were alternated with hypoxemia. Fetal hypoxemia was not associated with any change in fetal pH. During the first and second exposures to hypoxemia, there was an increase in fetal plasma lactate of 22.8 +/- 22.3 and 15.3 +/- 14.6 mg.dl-1 (mean +/- SD) above preliminary values (p less than 0.05) compared with the control period. Fetal plasma cortisol also increased by 5.7 +/- 6.1 and 9.5 +/- 5.4 ng.ml-1 (mean +/- SD) (p less than 0.05) compared with the control period. These results suggest that the fetal lamb at 122 to 139 days' gestation is highly sensitive to small decrements in Po2 of 5 mm Hg or less.

Digoxin-like substance in term pregnancy, newborns, and renal failure

Digoxin-like substance (DLS) is detected in pregnant women near term, newborns, and in patients with renal failure using RIAs for digoxin. We made "digoxin" measurements in such patients using three digoxin RIA kits (Nuclear Medical Laboratories (N), Clinical Assays (C), and Corning Magic (M]. At term mother DLS (micrograms/l digoxin) was 0-0.19 (N), 0.09-0.24 (C), 0.07-0.24 (M); cord blood DLS was 0.35-0.75 (N), 0.46-0.90 (C), 0.42-0.90 (M); infant DLS was 0.5-1.1 (N), 0.28-0.98 (C) and was not measured by M. DLS was detected at term in mothers and was essentially undetectable by 24 hr postdelivery. Cord levels fell in eight of ten infants to significantly lower levels by the second day of life. DLS in renal hemodialysis patients not receiving digoxin was 0.04-0.41 (N), 0.01-0.34 (C), 0.03-0.40 (M). While postdialysis levels by N tended to be lower than predialysis, they rose by C and M. Dilutions of cord blood yielded similar results by N, nonlinear decreases by C, and more nearly parallel decreases by M. In renal failure patients, dilutions yielded similar results by N and marked nonparallel results by M. Digoxin results obtained with immunoassays may be inaccurate in these patient populations. Digoxin immunoassays must be individually characterized as to the expected results.

Effect of hydralazine on intrapulmonary shunt

We compared the acute effects of bilateral arteriovenous may be related to levels of PvO2. The hydralazine-associated (p less than .05) decrease in resistance. Mixed venous oxygen fistulas to those of hydralazine infusion on hemodynamics and pulmonary gas exchange in dogs with pulmonary edema induced by administration of oleic acid. Oleic acid significantly (p less than .01) increased intrapulmonary shunt (Qsp/Qt) and pulmonary and systemic vascular resistance, and reduced cardiac output. Once the lesion stabilized, both opening the fistula and infusing hydralazine produced a similar and significant (p less than .01) increase in cardiac output, and a significant (p less than .05) decrease in resistance. Mixed venous oxygen tension (PvO2) closely followed the changes in cardiac output; however, PaO2 did not change. Qsp/Qt significantly (p less than .01) increased with the fistulas open and with hydralazine infusion. Closure of the fistulas or bleeding the animal at the end of the experiment reversed the changes in cardiac output and Qsp/Qt. The comparable increases in cardiac output and Qsp/Qt produced by opening the fistulas or infusing hydralazine may be related to levels of PvO2. The hydralazine-associated PvO2 increase indicates that this drug increased oxygen transport to the tissues even as Qsp/Qt became larger.

Effects of enhanced conventional therapy on metabolic control in children with insulin-dependent diabetes mellitus

We implemented a three-phase, 32-wk program to improve both self-regulation of adherence behaviors and insulin delivery in children with diabetes. Twenty children, aged 8-12 yr (mean duration 3.6 yr), enrolled. Phase 1 (wk 1-12) used behavior modification to improve diet, exercise, urine testing, and insulin adjustment, targeting an increased percentage negative urines. Feedback training and parent checks were used to improve reliability; adherence was measured using Clinitest placebos. Phase 2 (wk 13-20) was a stabilization period. Phase 3 (wk 21-32) studied the effect of insulin dose adjustment, comparing once-versus twice-daily shots in 10 pairs of children matched for %GHb. GHb, fasting plasma glucose, and lipids were measured at baseline and at the end of each phase. Results revealed a significant and sustained increase in negative urine tests, but no change in % GHb or FBG. Reliability of and adherence to urine tests were 83% and 76%, respectively. During phase 3, no significant differences were noted between groups receiving once- or twice-daily insulin injections. Thus, behavior modification resulted in increased reliability and adherence to routines, associated with a reliable increase in negative urines. This did not, however, produce changes in other control measures. Furthermore, no differences between those receiving 1 or 2 daily shots were evident.

[Mechanisms of conduction disorders in digitalis poisoning]

Ever since the first papers on the mechanism of the arrhythmias of digitalis were first published, during the first two decades of this century, the issue has been a controversial one. Since the automaticity induced by digitalis intoxication has different characteristics when compared to normal automaticity, it has been suggested that probably the mechanisms for these two types of spontaneous activity are different. It has been recently proposed that the automaticity induced by digitalis intoxication could be secondary to the after potential oscillations described in isolated conducting fibers. In order to test this hypothesis we used two experimental models which allow for a careful analysis of the ectopic activity, without the interference of the sinus rhythm. These studies were done in two groups of animals: one, with electrically isolated atria, was used to analyze supraventricular arrhythmias. The other, with chromic atrioventricular block, was used to study ventricular arrhythmias. The results obtained from these experiments show: 1. High therapeutic doses of digitalis enhance the postpacing inhibition of normal pacemakers; 2. When the ectopic rhythms of digitalis intoxication appear, they show postpacing stimulation; 3. Ectopic activity shows a direct relationship with the rate of the conditioning stimulation, and both the coupling period and the number of premature beats depend on this rate. In view of the similarity between the behavior of these arrhythmias and that of the after potential oscillations, we conclude that these oscillations are responsible for the ectopic automaticity of digitalis intoxication.

[Effect of sub-pressor doses of dopamine on renin secretion in the anesthetized dog]

The effects of dopamine, its precursor L-dopa, and the dopaminergic agonist bromocriptine (BEC), on plasma renin activity (PRA), in pentobarbital anesthetized male dogs were investigated. Infusion of dopamine at a dose which did not change blood pressure ( 4 ug/kg/min) had no effect on the secretion of renin, nor did it produce modifications in the PRA response to furosemide (10 mg i.v.). L-dopa, in single dose of 500 mg (p.o), significantly augmented PRA two hours after administration, and the renin values remained elevated throughout the observation period of 120 minutes. However, BEC (2.5 mg p.o.) produced no changes in PRA during this time period. We conclude that at the dose utilized, dopamine apparently has no influence on the secretion of renin, and does not modify the increase in PRA provoked by diuretic. It is possible that the L-dopa induced augmentation in PRA is due to stimulation of the juxtaglomerular cells, by the noradrenaline formed in peripheral tissues from administered L-dopa.

The effects of targeting improvements in urine glucose on metabolic control in children with insulin dependent diabetes

A treatment program designed to increase the percentage of negative urine tests was implemented using a multiple-baseline across groups design in a sample of 19 families of children with insulin dependent diabetes. The treatment involved instruction in insulin adjustment, decrease in intake of simple sugars and saturated fats, and increase in exercise, along with teaching the parents to support improvements in children's self-regulatory behaviors using a point economy and praise. New procedures designed to measure and reinforce adherence to the urine testing regimen were developed. Results showed significant increases in percentage of negative urines consistent with implementation of treatment across the three treatment groups, which were maintained over the follow-up period. Metabolic measures of control, including glycosylated hemoglobin and serum glucose did not show improvements even though the relationship between the percentage of negative urine tests and glycosylated hemoglobin was very high during treatment.

Zymosan-induced experimental hypersensitivity pneumonitis in rabbits

An experimental model of hypersensitivity pneumonitis is presented. New Zealand white rabbits, previously immunized against yeast-derived zymosan, reacted to intratracheal challenge developing extensive pneumonitis. The lesions healed in a few weeks. Control animals challenged with inert particulate material (latex beads) or suspending fluid (PBS-Mg++) did not show pulmonary inflammation. Nonimmunized rabbits developed only transient pneumonitis after zymosan challenge. This reaction was clearly different from that seen in the group of immunized animals. The model reveals that biologically active substances such as zymosan, which is able to activate the alternate pathway of complement and mononuclear phagocytes, requires an active immune state in order to cause significant tissue damage. Isolated exposure to this kind of substance may not be sufficient to cause lung disease.

Treatment of typhoid fever with fosfomycin alone and associated to chloramphenicol or ampicillin

Treatment with fosfomycin alone and associated to subtherapeutic doses of chloramphenicol or of ampicillin, has been tried on 50 patients with typhoid fever and on four carriers of S. typhi in the Hospital del Rey. 15 patients were treated with fosfomycin alone, 22 with fosfomycin plus chloramphenicol and 13 with fosfomycin plus ampicillin. The treatment lasted 15-20 days. The results have been evaluated clinically and bacteriologically, haemo- and coprocultures being carried out. The sensitivity of the isolated germs has been studied, including MIC and the synergism in vitro between fosfomycin-chloramphenicol and fosfomycin-ampicillin. Fosfomycin, chloramphenicol and ampicillin determinations have been carried out on the blood. The cures obtained were 67, 82 and 92% respectively with fosfomycin, fosfomycin-chloramphenicol and fosfomycin-ampicillin. We believe that this antibiotic can be useful in the treatment of typhoid fever, associating it to chloramphenicol or ampicillin, due to the synergism existing between them and given the results we have obtained.