Ribosomal protein P0, contrary to phosphoproteins P1 and P2, is required for ribosome activity and Saccharomyces cerevisiae viability

Protein P0 in Saccharomyces cerevisiae is found only in the ribosomes and not free in a cytoplasmic pool like the structurally related acidic P1 and P2 proteins. Analogously, P0 stays bound to the particles in conditions that release the other P proteins. Attempts to obtain yeast strains carrying an interrupted P0 gene by direct gene disruption techniques of different yeast strains always resulted in haploid cells carrying one disrupted and one intact copy of the gene. Disruption of the unique P0 genomic copy seems to induce a duplication and occasionally a chromosomal transposition of the gene. Conditional null mutants of P0 were then constructed carrying the P0 gene under the control of the inducible GAL1 promoter. A 2-3-fold excess of P0 mRNA is found in the conditional mutant when grown in galactose; however, only a small increase of the P0 protein is detected in total cell extracts. No P0 protein is detected in the cell supernatant, indicating that, like the standard ribosomal proteins and opposite to the other P proteins, the protein not bound to the ribosomes is degraded. Transfer of the mutants to the restrictive conditions causes, after some generations, a growth stop that finally leads to cell death. The growth decline is paralleled by a reduction in the polysome number and the appearance of half-mer particles as well as by an accumulation of 60 S particles deficient in P0 and in the acidic proteins P1 and P2. These results indicate that P0 is required for the interaction of the acidic P1 and P2 proteins with the ribosomes, and in its absence, deficient 60 S ribosomes are assembled which are inactive in protein synthesis resulting in cell lethality.

Sharing of injection equipment among 3755 intravenous drug users in Valencia, Spain, 1987-1992

BACKGROUND

In order to identify, in a sample of heroin intravenous drug users (IVDU), those factors associated with the predominant risk behaviour related to the transmission of HIV-1 infection--sharing of injection equipment--a cross-sectional survey was carried out in Valencia, Spain from 1987 to 1992.

METHODS

Informed consent and pertinent data were obtained from 3755 heroin IVDU recruited at two public AIDS Information Centres in two cities in the region of Valencia. Data were gathered on sociodemographic variables, and sexual and drug use behaviour by interview. The subjects were subsequently tested for HIV-1 antibody. A univariate analysis was carried out to identify variables that were significantly associated with sharing injection equipment. A logistic regression model was used to control for possible confounders.

RESULTS

The IVDU who were teenagers, prostitutes (OR = 1.95), who had antibodies to HIV-1 (OR = 1.30) or who had an IVDU steady partner were at significantly higher risk for sharing of injection equipment. Higher levels of education, condom use (OR = 0.65) and living in the smaller city (OR = 0.75) were inversely related to sharing injection equipment.

CONCLUSIONS

Our results suggest that different subgroups of IVDU have different characteristics that place them at different risk for HIV-1 infection. These characteristics should guide the design and intensity of specific preventive interventions. Teenagers and IVDU with low educational levels should be targetted for special attention by health authorities.

[Enalapril prevents myocardial remodeling in rats with arteriovenous fistula]

AIM OF THE STUDY

To evaluate the efficacy of enalapril in preventing cardiac myocyte remodelling in rats with arteriovenous fistulas.

EXPERIMENTAL DESIGN

We distributed thirty males Wistar rats in 3 groups: group A (control), group B (fistula) and group C (fistula + enalapril). An end to side fistula between the femoral artery and vein was produced in the right thighs of rats from groups B and C. Oral enalapril (0.07 mg/kg/day) was given to rats from group C. After 8 weeks the rats were sacrificed and their heart removed for pathologic study.

RESULTS

Body weight evolution was similar in all groups. Heart weight increased in group B (1.78 +/- 0.2 g) when compared to group A (1.55 +/- 0.11 g), (p < 0.02), and was similar (p = n.s.) in groups A and C (1.58 +/- 0.13 g). Heart weight/Body weight ratio was also increased in group B (4.4 +/- 0.55 mg/g) when compared to group A (3.6 +/- 0.5 mg/g), (p < 0.01), but was similar in groups A and C (3.66 +/- 0.4 mg/g) (p = n.s.). An increase in wall thickness was detected in group B in the right ventricle (p < 0.03), septum (p < 0.01) and left ventricle (p < 0.01) when compared to groups A and C. Myocytes cytoplasm volume fraction was increased in group B, when compared with group A, in all segments studied (right ventricle p = 0.011, septum p = 0.025, and left ventricle p = 0.031). Groups A and C were similar.

CONCLUSION

Enalapril prevents the structural remodelling of cardiac myocytes in this model of volume overload induced by an arteriovenous fistula.

Effects of PEEP on VA/Q mismatching in ventilated patients with chronic airflow obstruction

Recent work in patients with acute respiratory failure (ARF) due to exacerbation of chronic airflow obstruction (CAO) suggests that application of low degrees of positive end-expiratory pressure (PEEP) can improve rather than impair respiratory mechanics, because PEEP replaces intrinsic PEEP (PEEPi). However, the impact of PEEP on pulmonary gas exchange has not been fully investigated. We designed this study to examine the effects of PEEP and those of PEEPi on ventilation/perfusion (VA/Q) mismatching in mechanically ventilated patients with CAO. Eight patients were studied under four conditions: (1) during controlled mechanical ventilation with the ventilatory setting established by the attending physicians (PEEPi-100%), according to standard criteria; (2) after application of PEEP amounting to 50% (PEEP-50%), and then (3) to 100% (PEEP-100%) of the original PEEPi; and finally, (4) after reduction of PEEPi to 50% of the initial value (PEEPi-50%), obtained by increasing expiratory time and decreasing respiratory rate and tidal volume. Respiratory mechanics, hemodynamics, respiratory blood gases, and VA/Q distributions were measured during each ventilatory mode. At low values of PEEP (PEEP-50%) no changes in respiratory mechanics nor in hemodynamics were observed, but PaO2 moderately increased (from 103 +/- 25.2 to 112 +/- 29.6 mm Hg) and PaCO2 slightly decreased (from 42 +/- 3.7 to 40 +/- 3.3 mm Hg) essentially because of an increase in the mean VA/Q ratio (first moment) of both flood flow (Q, from 0.65 +/- 0.28 to 0.78 +/- 0.29) and ventilation (V, from 4.02 +/- 1.55 to 4.93 +/- 2.00) distributions (p < 0.05, each).(ABSTRACT TRUNCATED AT 250 WORDS)

Laminin and tenascin assembly and expression regulate HC11 mouse mammary cell differentiation

HC11 is a normal mouse mammary epithelial cell line that requires certain growth factors, such as EGF or bFGF, to respond optimally to lactogenic hormones and produce the differentiation marker beta-casein. Growth in insulin (Ins) or PDGF does not produce cells competent to respond to lactogenic hormones. Here we show that competency for differentiation is due at least in part to the modulation of extracellular matrix components. In particular we have studied laminin and tenascin. EGF alters endogenous laminin assembly. In addition, promotion of competency can be partially mimicked by plating HC11 cells on the E8 laminin fragment, which is able to induce lactogenic responsiveness in cells grown in the absence of EGF or bFGF. The production and assembly of tenascin is also dependent upon the growth conditions of the HC11 cells. EGF- or bFGF-grown competent cells produce tenascin but do not assemble it at the extracellular matrix as efficiently as Ins- or PDGF-grown, non-competent cells. This alteration apparently leads to a change in the cellular microenvironment that supports beta-casein production. In addition, when competent cells are plated on dishes coated with tenascin, lactogenic hormone induction of beta-casein is inhibited. The data suggest that tenascin assembly and beta-casein production are opposing features of a coordinated differentiation program of HC11 cells.

Effect of acidic ribosomal phosphoprotein mRNA 5'-untranslated region on gene expression and protein accumulation

Constructions were made from genes encoding ribosomal acidic phosphoproteins YP1 beta (L44') and YP2 beta (L45) from Saccharomyces cerevisiae in which different parts of the 5'-untranslated regions were included. The constructs were inserted into centromeric plasmids under the control of the GAL1 promoter and expressed in yeast strains in which the genes coding for each acidic protein family, P1 and P2, had been disrupted. Deletions in the 5' region of the two genes have been found to oppositely affect their expression. Deletion of most of this region strongly stimulates the expression of YP2 beta (L45), increasing the translation efficiency of the mRNA, and generating a 6-fold excess of protein in the cell. A similar deletion in the rpYP1 beta gene represses the expression of the protein, reducing drastically the amount of the mRNA in the cell. The overexpression of rpYP2 beta affects the cell growth by inhibiting protein synthesis at the level of initiation. Reduction of the YP2 beta(L45) overproduction by growing in controlled concentrations of glucose abolishes the inhibitory effect. The excess protein, probably as a high molecular weight complex, apparently interferes with the joining of the 60 S subunit to the initiation complex generating the accumulation of polysome half-mers. In addition, the results indicate the existence of a regulatory mechanism by which each one of the two acidic proteins controls the expression of the other polypeptide. YP1 beta(L44') represses the expression of YP2 beta(L45), while this protein stimulates the expression of YP1 beta(L44').

Formation of hydroxyl radicals and Co3+ in the reaction of Co(2+)-EDTA with hydrogen peroxide. Catalytic effect of Fe3+

Co2+ ions (Co(NO3)2.6H2O) react with H2O2 only in presence of EDTA to yield OH radicals and Co3+. This reaction was carried out in unbuffered aqueous solutions (pH = 2.6). The formation of Co3+ was confirmed by spectroscopy. The Co(3+)-EDTA complex shows two typical absorptions at 382 nm and 532 nm. The Co(3+)-EDTA complex can be prepared by a number of oxidizing agents, like Fe3+, Fe(3+)-EDTA, Ag+, Ag2+, Ce4+, and hydroxyl radicals. Since Fe3+ oxidizes Co(2+)-EDTA to Co(3+)-EDTA and Fe2+ we initiate a chain reaction for .OH formation. Our results show that there are two modes for H2O2 decomposition: (1) One electron transfer to give OH radicals and (2) Decomposition of H2O2 to H2O and O2 without intermediate .OH formation. This reaction depends strongly on the pH of the buffer. The H2O2 decomposition increases with increasing pH and increasing Co2+ concentration.

The acidic phosphoproteins from Saccharomyces cerevisiae ribosomes. NH2-terminal acetylation is a conserved difference between P1 and P2 proteins

Isoelectrofocusing gels of acidic ribosomal proteins from most yeast strains reveal the presence of up to 10 bands which are the product of only 4 genes. The proteins have been characterized by NH2-terminal amino acid sequencing, specific antibodies, HPLC, and by taking advantage of acidic protein-defective yeast strains obtained by gene disruption methods. The four most basic proteins coincide with the phosphorylated and dephosphorylated forms of the YP2 proteins, YP2 alpha and YP2 beta, formerly named L44 and L45. Amino-terminal sequencing has shown that these two polypeptides have free amino-terminal ends starting at the first methionine residue. The bands defined earlier as L44' correspond to the phosphorylated and dephosphorylated processed forms of protein YB1 beta lacking the first eight amino acids. The formation of this truncated YP1 beta form seems to be stimulated by salt during protein extraction and is also favored by some modifications at the amino termini of the protein. On the other hand, the previously uncharacterized band, called Ax, corresponds to an NH2-terminal acetylated form of YP1 beta which starts at the serine in the second position of the nucleotide-derived sequence. Finally, the most acidic band is the phosphorylated product of the fourth acidic protein gene. This protein, called YP1 alpha, which is very poorly stained by silver and Coomassie blue, has not been characterized in detail previously. It is also monophosphorylated in the ribosome and, like YP1 beta, is present as an NH2-terminal acetylated form starting at the second serine residue.(ABSTRACT TRUNCATED AT 250 WORDS)

Leukonychia due to cytostatic agents

Chromonychia induced by antineoplastic agents has been known for several years. The most frequent of these is melanonychia, either diffuse or in tranverse or longitudinal bands, that may co-exist with diffuse pigmentation of the skin. Although any cytostatic agent may be involved in melanonychia, this condition appears most commonly after treatment with adriamycin and cyclophosphamide or in polychemotherapy. Leukonychia, either true or apparent, seems to be less frequent and is the reason for our reporting two patients with this colour change.

Stable binding of the eukaryotic acidic phosphoproteins to the ribosome is not an absolute requirement for in vivo protein synthesis

The genes encoding the four acidic ribosomal phosphoproteins have been inactivated in Saccharomyces cerevisae by recombination with truncated genes carrying different genetic markers. By crossing single haploid disruptants, strains harboring two simultaneously inactivated acidic protein genes were constructed. None of the six possible double disruptions was lethal, but the simultaneous inactivation of either YP1 alpha and YP1 beta(L44') or YP2 alpha(L44) and YP2 beta(L45) caused an important decrease in the cell growth rate. Ribosomes isolated from these slow-growing strains did not contain acidic proteins, not even the two polypeptides whose genes were still intact, although these proteins were present in the cell extracts and they seem to be able to form high-molecular weight protein complexes. Transformation of a slow-growing double transformant with a plasmid containing one of the disrupted genes restored the presence of the acidic proteins in the ribosomes and normal growth rates. The particles of the slow-growing strains were active in an in vitro amino acid polymerizing system, although their activity could be stimulated by the exogenous addition of the missing proteins. These results indicate that in the absence of either YP1 alpha and YP1 beta(L44') or YP2 alpha (L44) and YP2 beta(L45), the remaining acidic proteins are unable to interact with the ribosome in a stable manner, but that a strong interaction of these ribosomal components with the particle is not an absolute requirement for in vivo and in vitro protein synthesis.

[Trials of acute treatment with SMS 201-995 in acromegalics]

The results of two acute treatment tests using SMS 201-995 (SMS), over a 24 hour period in acromegalic patients are presented. Test number 1: Seventeen cases with a mean age of 44.3 +/- 11.9 (21/71) years with an evolution of 9.2 +/- 6.5 (2/20) years and GH of 30.1 +/- 21.1 (5.2/96.4) ng/ml were treated with 50 micrograms/8 hours (8, 16, and 24 hours) of subcutaneous SMS. Test number 2: 26 cases with a mean age of 45.5 +/- 15.5 (21/71) years with an evolution of 9.1 +/- 7.9 (2/35) years and GH of 28.6 +/- 22.2 (5.2/96.4) ng/ml were treated with 100 micrograms/8 hours (8, 16, and 24 hours) of subcutaneous SMS. Ten point GH profile in 24 hours is evaluated in both tests and in number 2 insulin and blood sugar levels are measured at the same time points. In both tests GH is significantly reduced being the 100 micrograms/8 hour treatment schedule more efficient. The results in the decrease of GH in test number two are related to those obtained using SMS in prolonged treatments. Inspire of the reducing effect that SMS has on insulin levels, its influence on the blood sugar profile is scare.

Identification of human papillomavirus type 16 in primary and recurrent cervical cancer following radiation therapy

Formalin-fixed, paraffin-embedded tissue blocks from 13 women with cervical carcinoma that recurred following radiation therapy were evaluated for the presence of human papillomavirus (HPV) by in situ hybridization using ribonucleic acid 35S-labeled probes for HPV types 6, 11, 16, and 18. Ten of thirteen patients also had pretreatment biopsies from their primary tumors available for analysis. HPV 16 was detected in both primary and recurrent lesions in 4 women. In 1 case, HPV was detected in the primary tumor and not in the recurrence. HPV 16 was also present in three recurrent cancers from which primary lesions were not available for probing. Radiation therapy did not alter the hybridization signal strength or pattern, suggesting that the HPV genome copy number was not significantly affected. The persistence of HPV 16 in recurrent cervical carcinoma is consistent with the theory that HPV plays a role in maintaining the malignant state.

[Comparative study of peridural anesthesia with bupivacaine alone and combined with fentanyl during vaginal delivery]

Two groups of primiparous women with single fetus in cephalic presentation were prospectively randomized at the end of pregnancy to receive epidural analgesia with 0.25% bupivacaine, either single (n = 102) or associated with 0.05 mg of phentanyl (n = 102). Phentanyl significantly reduces the period of development of analgesia and increases the interdose period. The quality of analgesia is significantly better when fentanyl is associated with bupivacaine. The evolution of delivery (dilatation and expulsion) and the perinatal results (cord pH and vitality of the newborn as assessed by the Apgar test) were similar in both groups. We conclude that the association of phentanyl with bupivacaine has advantages for epidural analgesia during delivery, as the quality of analgesia is improved, its duration is prolonged and there are no adverse effects on the evolution of delivery or on the newborn.

[Results of trans-sphenoidal surgery for the treatment of acromegaly]

During the past 17 years (1972-89) 55 transsphenoidal surgery (TSS) interventions were performed in our Hospital in 53 cases of acromagaly (2 cases underwent surgery twice).

RESULTS

22 were cured (40%); 15 partial efficacy (27%) and 18 negative efficacy (33%). Mean GH values (ngr/ml) before surgery were: Cured cases 15.8 + 12.9 (p = 0.0015). Basal GH values above 40 ngr/ml obscure the prognosis of TSS in acromegaly. Cure was perfectly achieved in smaller size hypophysis adenomas (Hardy Grade land 11 in CT scan). The complications in the early post-surgery were rare and transient. Chronic sequelae due to TSS occurred in 7 cases (13.5%), as complete or partial anterior hypophysis failure. TSS is the treatment of choice of acromegaly in our environment, however a significant number of cases do not achieve cure and need to complete treatment with hypophyseal radiotherapy.

Disruption of single-copy genes encoding acidic ribosomal proteins in Saccharomyces cerevisiae

Using the cloned genes coding for the ribosomal acidic proteins L44 and L45, constructions were made which deleted part of the coding sequence and inserted a DNA fragment at that site carrying either the URA3 or HIS3 gene. By gene disruption techniques with linearized DNA from these constructions, strains of Saccharomyces cerevisiae were obtained which lacked a functional gene for either protein L44 or protein L45. The disrupted genes in the transformants were characterized by Southern blots. The absence of the proteins was verified by electrofocusing and immunological techniques, but a compensating increase of the other acidic ribosomal proteins was not detected. The mutant lacking L44 grew at a rate identical to the parental strain in complex as well as in minimal medium. The L45-disrupted strain also grew well in both media but at a slower rate than the parental culture. A diploid strain was obtained by crossing both transformants, and by tetrad analysis it was shown that the double transformant lacking both genes is not viable. These results indicated that proteins L44 and L45 are independently dispensable for cell growth and that the ribosome is functional in the absence of either of them.

[Treatment of macroprolactinomas with delayed bromocriptine. Effectiveness of a single intramuscular injection]

The aim of the present study was to evaluate the effectiveness and tolerance of a new pharmaceutical preparation of long acting bromocryptine (bromocryptine depot of L.A.), characterized by the slow release of bromocryptine during 4 or 6 weeks after a deep intramuscular injection. It was administered to 9 patients with macroprolactinoma, 7 of which had visual abnormalities. The tolerance of the drug was excellent, and only one patient had nausea within the first 24 hours. In all cases, PRL values fell between 40% and 97%. All patients with visual abnormalities, including 2 patients with cranial nerve palsy (IIIth and VIIth pairs) returned to normal or improved. In the CT controls carried out after 4 weeks of therapy a reduction in tumor size was observed in 7 of 9 patients. Two patients were operated through the transesphenoidal route, PRL being demonstrated in the immunohistochemical study of the resected specimen. Subsequently, all patients received oral bromocryptine therapy with perfect tolerance. The results show that parenteral long acting bromocryptine is an effective, well tolerated and convenient way to start the therapy of macroprolactinoma, even when severe visual abnormalities are present.

[Acanthosis nigricans and cancer of the stomach]

A case of a 44 years old patient with inoperable gastric adenocarcinoma and exuberant lesions of Acanthosis Nigricans is described. He died nine months after the diagnosis, having experienced disappearance of the cutaneous manifestations after the cytostatic treatment done. The literature about Acanthosis Nigricans is reviewed and the importance of precocious search of associated malign disease is stressed. It was demonstrated by immunocytochemistry, positivity to NSE (neuron specific enolase) and ACTH, in the patient gastric tumour cells which allows them to be classified as neuroendocrine cells. It is suggested that Acanthosis Nigricans is a manifestation of a para-endocrine syndrome.