Comparison of the enzymatic properties of the Na,K-ATPase alpha 3 beta 1 and alpha 3 beta 2 isozymes

The coexpression of multiple isoforms of the alpha and beta subunits of the Na,K-ATPase in mammalian tissues gives rise to the complex molecular heterogeneity that characterizes the Na pump. The expression of the different Na,K-ATPase isoforms in insect cells using recombinant baculoviruses represents a useful system for the analysis of Na,K-ATPase isoform function. In the present study, we use this system to direct the expression of the rat Na,K-ATPase alpha 3 beta 1 and alpha 3 beta 2 in sf-9 cells, a cell line derived from the ovary of the fall armyworm, Spodoptera frugiperda. The association of alpha 3 with either beta 1 or beta 2 results in catalytically competent Na,K-ATPase isozymes. Analysis of the kinetic characteristics of these enzymes demonstrates that the accompanying beta subunit isoform does not drastically affect the properties of the alpha 3 polypeptide. This is evidenced by the similar turnover numbers, apparent affinities for K+ and ATP, and the comparable high sensitivity to ouabain exhibited by both isozymes. The kinetic dependence on Na+, however, is different for both isozymes, with alpha 3 beta 2 displaying a 1.6-fold higher apparent affinity for the cation than alpha 3 beta 1. Comparison with other Na,K-ATPase isozymes shows that the apparent Na+ affinity of alpha 3 beta 2 is similar to that of the alpha 1 beta 1 Na pump widely expressed in every tissue; nevertheless, its reactivity toward K+, ATP, and ouabain are characteristic of the alpha 3 isoform. The most pronounced kinetic differences in Na,K-ATPase function are a result of variations in alpha isoform composition.(ABSTRACT TRUNCATED AT 250 WORDS)

[Drug prescriptions in general medicine practice]

OBJECTIVE

To find the origin of pharmacological prescriptions written in the primary care ambit, the effect of training on the prescribers and the influence of the organisational structure of the centres where they work on the quality of the drugs prescribed.

DESIGN

Observational study of a crossover type.

SETTING

Two health centres and two consulting-rooms in Areas 11 and 12, Valencia.

MEASUREMENTS AND MAIN RESULTS

The sample calculated corresponded to 664 prescriptions per centre. The origin of the prescription differed, depending on the model, so that in the consulting-rooms the origin of 55% of prescriptions was specialist care, whereas in the health centres this percentage went down to 31%. There were significant differences (p < 0.0001) in the quality of prescription in different organisational structures, but there were no significant differences among professionals with different training.

CONCLUSIONS

A high percentage of pharmacological prescriptions have their origin in specialist care. Prescription quality is conditioned basically by the organisational model and is appreciably better in health centres.

Kinetic properties of the alpha 2 beta 1 and alpha 2 beta 2 isozymes of the Na,K-ATPase

The presence of multiple isoforms of the alpha and beta subunits of the Na,K-ATPase in most mammalian tissues has hindered the understanding of the roles of the individual isoforms in directing Na,K-ATPase function. Expression of the Na,K-ATPase subunits in insect cells using recombinant baculoviruses has proven to be a useful system for the study of Na,K-ATPase function. Using this system, we have expressed the rat Na,K-ATPase alpha 2 beta 1 and alpha 2 beta 2 isoforms in Sf-9 insect cells, a cell line derived from the ovary of the fall armyworm, Spodoptera frugiperda. Both beta 1 and beta 2 isoforms can efficiently assemble with the alpha 2 subunit to produce catalytically competent Na,K-ATPase molecules. The analysis of the kinetic properties of both isozymes showed that alpha 2 beta 1 and alpha 2 beta 2 have equivalent sensitivities to ouabain, and similar turnover numbers and apparent affinities for K+ and ATP. The dependence on Na+, however, differs between the isozymes, with alpha 2 beta 2 displaying a slightly higher apparent affinity for the cation than alpha 2 beta 1. In addition, the even greater kinetic differences between Na,K-ATPase isozymes varying in alpha isoforms may be important in further differentiating the enzyme. Thus, when compared to the rat alpha 1 beta 1 Na,K-ATPase expressed in Sf-9 cells, the alpha 2 beta 1 and alpha 2 beta 2 isozymes have a lower apparent affinity for K+ and a higher affinity for Na+ and ATP.(ABSTRACT TRUNCATED AT 250 WORDS)

AMPA/KA receptor induced AP-1 DNA binding activity in cultured Bergmann glia cells

The effect of L-glutamate (L-Glu) and its structural analogs kainate (KA) and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) on the DNA binding activity of the activator protein 1 (AP-1) family of transcription factors was examined in cultured chick cerebellar Bergmann glia cells. These agonists evoked a dose- and time-dependent increase in AP-1 DNA binding activity and their responses were blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). The increase in DNA binding is probably mediated by an AMPA/low affinity KA subtype of L-Glu receptor. The synaptic localization of these receptors, their ion channel properties and a stimulus-transcription coupling further strengthen the putative role of glia cells in the modulation of synaptic efficacy and plasticity.

[Comparative study of intravenous anesthesia with propofol in continuous perfusion and neuroleptanalgesia in traumatology surgery]

OBJECTIVE. To study propofol as the single agent for both anesthetic induction and maintenance with respect to quality of anesthesia, hemodynamic effects, quality of recovery and analgesic requirements in comparison with neuroleptoanesthesia as the technique of reference. PATIENTS AND METHODS. We selected 2 homogeneous groups of 15 ASA I-III patients undergoing traumatological surgery. Patients were premedicated with bromazepam 3 mg p.o. and droperidol 0.03 mg/kg prior to induction. Induction was achieved with propofol 1.5-2.5 mg/kg in group I (GI) and with sodium thiopental 4-5 mg/kg in group II (GII). Maintenance was by continuous infusion of propofol 6-12 mg/kg in GI and with droperidol 0.15 microgram/kg/h and 50% N2O/O2 in GII. Both groups received fentanyl 4 micrograms/kg/h. Neither analgesia nor curarization were antagonized pharmacologically. Variables recorded were time and quality of anesthetic induction, mean duration of anesthesia, anesthetic education time, time until orientation and time of residual analgesia. Hemodynamic parameters were recorded for both groups at baseline, after induction, at intubation, at 2 and 5 min after intubation, at the start of surgical incision, 30 min after start of incision, and at the end of surgery. Results for the two groups were compared, as were results at the various moments of measurement within groups.

High level expression of the B. microplus Bm86 antigen in the yeast Pichia pastoris forming highly immunogenic particles for cattle

Recently, a gene coding for the Bm86 tick gut glycoprotein was cloned, expressed in Escherichia coli and shown to induce an immunological response in cattle to damage ticks engorging on these animals (Rand et al., 1989). We report here the increased expression of the Bm86 antigen from the cattle tick Boophilus microplus in the methylotrophic yeast Pichia pastoris. The recombinant protein was obtained with a purity higher than 95% by a procedure with a high yield. The conducted biochemical studies demonstrated the antigen to be glycosylated and found to form particles of around 17 to 45 nm in diameter with enhanced immunogenic properties. Ticks engorging on vaccinated cattle were significantly damaged as a result of the immune response against the recombinant antigen. This system permits the obtainment in a high yield of the tick Bm86 antigen, in a glycosylated and particulated form.

Multiepitope polypeptide of the HIV-1 envelope induces neutralizing monoclonal antibodies against V3 loop

A gene encoding a multiepitope polypeptide (MEP) has been synthesized. It contains the information for (1) an 11-amino acid (aa) epitope from the C1 region of gp120 of HIV-1 and (2) 3 epitopes of 15 amino acids each, from the central part of the V3 loop of isolates MN, SC, and WMJII. These four segments are linked by the short spacer peptide AGGGA. This gene was cloned in a plasmid vector and expressed in Escherichia coli as a fusion product with a 62-aa fragment of human IL-2. The recombinant protein TAB1 was purified by washed pellet procedures and reversed-phase HPLC. TAB1 was recognized in ELISAs by 25 of 27 sera from seropositive individuals. Mice were immunized and several hybridomas were obtained. Two of them secrete monoclonal antibodies that react with synthetic peptides from isolates MN, WMJI, WMJIII, and SC with an affinity constant in the range of 10(8) M-1. They also recognized peptides from isolates SF2 and WMJII, but at much lower affinity. The results obtained from peptide ELISAs indicate that the putative epitope recognized by these MAbs lies within the sequence IHIGPGRAFYT. Classic neutralization assays demonstrated that MAb 2C4 neutralizes 50% of the MN isolate at 0.6 micrograms/ml but fails to neutralize IIIB and SF2 strains. The presence of antibodies directed against every one of the component peptides in the sera of rabbits immunized with TAB1 was also documented.

[Hepatitis C virus antibodies in chronic non-alcoholic liver disease]

The presence of hepatitis C virus antibodies was studied in 64 patients with non alcoholic liver disease and found in 11 (17%). The greater frequency of positive antibodies was found among patients with cryptogenetic liver disease, specially those without serum auto-antibodies (32%). The antibody was unusually found (0 to 11%) in non alcoholic liver diseases of other etiologies. It is concluded that hepatitis C virus chronic infections may be the etiology of an important number of non alcoholic chronic liver diseases.

[Clinical and etiologic study of 90 cases of chronic diarrhea]

90 patients with chronic diarrhoea underwent this prospective study. They were seen in a private hospital of Lima during 1990 and 1991. According to a methodologic plan for determining sources and the diseases that originate chronic diarrhoea. In all patients hematologic, bioquimic, coprocultures, coproparasitologic exams were done, chest and intestinal transit X-rays. All underwent duodenal content culture. Colon X-ray in 25 cases; proctosigmoidoscopy in 14 and upper digestive endoscopy in 19 patients. Abdominal echography in 12 and TAC in 2 cases. The final results showed as determinant diseases for chronic diarrhoea, according to their frequency: enteroparasitosis (23.3%), functional digestive disorders (20.0%), intestinal bacterial overpopulation (15.5%) of unknown origin (8.8%), colon diverticulus (7.7%) proven and probably (5.5%), lactose intolerance (3.3%), diabetes mellitus (2.2%), and in one case (1.1%) the following: intestinal linfoma, pancreas malignancy, AIDS, colonic and deformation and megaloblastic anemia. The causes of chronic diarrhoea are several and multifactorals and in this study we prove the preeminence of the intestinal parasitosis, functional disorders and intestinal bacterial overpopulation and with less frequency other pathologies.

Characterization of cholinesterase activities in primary cultures of retinal pigment epithelium

This report presents a comparative description of the acetylcholinesterase and butyrylcholinesterase activities and their molecular forms in primary cultures of retinal pigment epithelium (RPE). Acetylcholinesterase activity increases during differentiation of the cells. Sucrose sedimentation analysis of acetylcholinesterase and butyrylcholinesterase molecular forms revealed the presence of A12, G4, G2, and G1 and A8, G4, G2 and G1, respectively. RPE cells in culture release both cholinesterases into the growth medium, sedimenting as the G4 molecular form. Changes in the molecular forms of both enzymes were observed during differentiation. The results suggest a possible relationship between butyrylcholinesterase activity and cell proliferation and acetylcholinesterase activity and cell differentiation.

[HIV infection. Diagnosis in the national network of laboratories in Chile]

A national network including 114 blood banks and laboratories performs screening for HIV infection on approximately 250,000 blood donors a year. This represents 100% coverage of blood transfusions performed in Chile. Up to December 1990. 4956 samples had been sent to the National Reference Center for AIDS for supplementary studies. HIV infection was confirmed in 1465 (29.6%). A prior study covering the first semester of 1989 showed a 26.9% confirmation rate for HIV infection on 845 serum samples. Technical errors including sample contamination, poor cleaning, decreasing titers of controls and erratic criteria regarding the need for supplementary studies may explain the low confirmation rate reported in this study.

[Acute retroviral syndrome]

A 37 year old male developed fever for 20 days, along with headache, anorexia, malaise, sweating, pharyngitis, lymphadenopathy and splenomegaly. At this stage, Ag p24 was positive and anti HIV was negative. The patient recovered fully but 6 months later positive HIV titers were demonstrated by immunofluorescence and Western-blot. A retrospective diagnosis of acute retroviral syndrome was made. The difficult differential diagnosis with infectious mononucleosis, cytomegalovirus, measles, rubella, toxoplasmosis and influenza is discussed. Thus, anti HIV antigenemia should be investigated in any patient with a mononucleosis like syndrome belonging in a high risk group for AIDS, even if Paul-Bunnell-Davidson or IgG anti VCA-EB reactions are positive.

[Patients with an indeterminate serological diagnosis of HIV-1 infection]

Western blot is the technique most frequently used to determine the presence of HIV-1 antibodies. However, some patients remain with an indeterminate diagnosis for HIV-1 according to the technique. We followed 8 such patients for 2 to 18 months. Immunologic studies included standard ELISA, immunofluorescence and Abbott anti-p24 ELISA. We found selective reactivity for certain viral proteins such as isolated p24, p24 plus p51 or p55, gp41 plus gp 120, p17 plus p24 and p25.

[Immunity status of 2 Chilean female populations against rubella]

A total of 1248 females were studied to determine immunity against rubella. A higher socio-economic subgroup (n = 789) and a lower one (459) were defined. Inhibition of hemagglutination was used to detect immunity. Positive results were obtained in 95% of females and no differences were detected for both groups. 78% of positive titers fell in the dilution range 1:20 to 1:80.

[Penile erection after spinal anesthesia. Treatment with intracavernous ethyladrianol]

We report on 26 patients with sustained penile erection from spinal anesthesia following the classical technique using 20 mg bupivacaine at 0.25% that were treated by intracavernous injection of 10 mg ethyladrianol. Complete detumescence was achieved in 23 (88.4%); partial detumescence, which permitted transurethral surgery, was achieved in 3 patients (11.6%). No complications were observed apart from mild hematoma at the site of injection in 2 patients. All patients presented easily controllable arterial hypertension. This is a simple, easy and practically risk-free technique that has the advantage of achieving a high response rate thereby permitting surgery.

[Evaluation of 2 methods for studying slime production by coagulase-negative Staphylococcus strains]

The surface hydrophobicity and the slime production of 46 coagulase negative staphylococci isolated from the urine, blood and skin were evaluated. The hydrophobicity values were very heterogeneous and did not correlate with the species, origin or slime production. Slime production was evaluated by the classical tube method and by a micromethod with spectrophotometric readings. There was a high correlation between both methods, but the results were more reproducible and quantifiable with the latter. Twenty-six of the evaluated species produced some degree of slime. This feature did not correlate with their origin or species. The preincubation of 5 strains of Staphylococcus epidermidis with subinhibitory concentrations of vancomycin, clindamycin and amikacin did not influence slime production, whereas ciprofloxacin slightly inhibited it in two strains and oxacillin completely inhibited slime production in the five evaluated strains.

Identification of biliprotein as a liver growth factor

We determined the concentration of biliprotein in plasma of rats at different times after partial hepatectomy. From the same plasma samples, we purified a liver growth factor previously characterized by our group. When we plotted the 14 points studied, a linear relationship was obtained (r = 0.999; p less than 0.001). This result, in addition to our group's recent identification of this liver growth factor as an albumin-bilirubin complex, strongly suggests that biliprotein is a liver growth factor.

A liver DNA synthesis promoter induced in rat plasma by injection of dimethylnitrosamine (DMNA) or thioacetamide

The appearance of a liver DNA synthesis promoter (HP) in rat plasma after dimethylnitrosamine (DMNA) or thioacetamide injection was investigated. After 48 h, DMNA (30 mg kg-1 body weight) produced liver (centrilobular) necrosis and intense hepatic regeneration, as assessed by microscopic observations of liver slices, as well as augmented transaminase levels; HP was detectable under these conditions. After 5 days, transaminases and HP returned to normal values (the latter undetectable), coinciding with a lack of necrotic zones. At 60 mg DMNA kg-1 body weight, necrotic areas were more marked and transaminases and HP levels higher after 48 h than with the lower dose; these increases were even more pronounced at 90 mg DMNA kg-1 body weight. After thioacetamide injection (200 mg kg-1 body wt) the situation at 48 h was very similar, with focal, centrilobular necrosis, frequent regenerative signs, high transaminases and detectable HP. Rats recovered after 7 days in a similar fashion as with DMNA. At 400 mg thioacetamide kg-1 body weight, necrotic areas and regeneration zones were more widespread and transaminases and HP higher after 48 h than with the lower dose. On account of the differing modes of action of DMNA and thioacetamide in rat liver, it is proposed that the appearance of HP activity in plasma could be related to the regenerative process that follows hepatotoxic damage.

Identification of a liver growth factor as an albumin-bilirubin complex

We have reported the purification and characterization of a protein that behaves as a liver growth factor, showing activity either in vivo or in vitro [Díaz-Gil et al. (1986) Biochem. J. 235, 49-55]. In the present paper, we identify this liver growth factor (LGF) as an albumin-bilirubin complex. This conclusion is supported by the results of chemical and spectroscopic characterization of this protein as well as by experiments in vivo. Incubation of albumin isolated from normal rats with bilirubin/albumin molar ratios (r) resulted (when r = 1 or 2) in a complex with liver DNA synthesis promoter activity identical with that of LGF. The exact amount of bilirubin bound to albumin was assessed by fluorescence and c.d. spectra. This albumin-bilirubin complex showed the same dose-dependence profile as LGF either at low or high dose of protein injected per mouse. Both LGF and albumin-bilirubin complex produced similar increases in the mitotic index of mouse hepatocytes in vivo. A new mechanism for the onset of the hepatic regenerative process is proposed.

[Stimulation of the central dopaminergic receptor in essential hypertensive patients using amantadine]

At present, evidence has been accumulating that point out that some central nervous structures, of oblongata to the limbic system, are primarily involved in the control of systemic arterial pressure (AP). In agreement with several experimental and clinical works, a hypothesis has been suggested that a functional defect of the central dopaminergic system could be involved in the etiopathogenesis of essential hypertension (EH). With the objective of analyzing this hypothesis, the effect of dopamine (DA) agonist, amantadine (Am) on heart rate (HR), AP, plasma catecholamines (CA, PCA), urinary DA, noradrenaline (NA), adrenaline (A), vanilmandelic acid (VMA) and homovanillic acid (HVA), was studied in 19 females with established EH. The study included 2 periods: "placebo" and "drug", each one lasting 22 days, with a register of HR and AP in clino and orthostatism, taken every 3-4 days; at the end of each period, CA and their metabolites were measured. During the drug period, oral Am clorhidrate (300 mg/day, t.i.d.) was administered. With the drug, HR was not change with respect to the placebo period; but the AP in both positions, just as PCA, DA, NA and HVA, showed a highly significant decrease; A and VMA displayed a less significant decrease from the statistical point of view. The obtained results and literature data support the hypothesis that in EH there probably exists a genetic disfunction of the inhibitory central dopaminergic receptor of peripheral sympathetic activity, which is susceptible to compensation by use of several dopaminergic agonists, such as Am.