Analysis of phenotypic consequences of renin gene polymorphism in Lyon rats

OBJECTIVE

To investigate phenotypic consequences of renin gene polymorphism between Lyon hypertensive (LH) and normotensive (LN) rats because previously we demonstrated cosegregation of the LH allele with increased blood pressure in a cross of LH with LN rats.

DESIGN

Two studies were conducted. Study 1 used a cohort of male F2 rats from a LH x LN cross. Eighty-two rats homozygous for the hypertensive (HH) renin gene allele were compared with 82 rats homozygous for the normotensive (NN) allele. Urinary steroid excretion was measured in 24 h urine samples collected from rats aged 6 weeks. The direct aortic blood pressure was recorded in 30-week-old rats and, after they had been killed, their kidney renin concentration (KRC) was measured. In study 2, renin, angiotensinogen and angiotensin converting enzyme plasma concentrations and renin messenger RNA (mRNA) levels were measured in renal and extra-renal tissues from 6- and 25-week-old LH and LN parental and HH and NN F2 male rats.

METHODS

Urinary steroids and plasma components of the renin-angiotensin system (RAS) were measured using specific radioimmunoassays. mRNA levels were quantified by northern blotting.

RESULTS

In study 1, HH F2 rats had a higher blood pressure (151.5 +/- 8.2 versus 146.0 +/- 7.4 mmHg, P < 0.001) and a lower KRC (514 +/- 203 versus 666 +/- 304 micrograms A1/h per g cortex, P < 0.01) than did NN rats aged 30 weeks. In covariate analysis the decrease in KRC in HH rats was attributable to their increased blood pressure rather than to the renin genotype. The renin genotype of rats aged 6 weeks was not associated with a change in the urinary excretion of aldosterone, desoxycorticosterone, corticosterone or 18-hydroxy desoxycorticosterone. In study 2, we found no difference either in plasma levels of RAS components or in renal or extrarenal renin mRNA levels either between parental LH and LN rats or between HH and NN F2 rats apart from a higher plasma renin concentration in LH rats aged 6 weeks. Renal, but not extra-renal, renin mRNA levels declined with age.

CONCLUSIONS

We found no evidence of a renin genotype-dependent phenotypic difference in the RAS that could account for the effect of the renin locus on blood pressure in Lyon rats. Our findings suggest that the effect of the locus on blood pressure might be due to an as yet unidentified gene linked to renin.

Cloning and expression of a complementary DNA encoding a molluscan octopamine receptor that couples to chloride channels in HEK293 cells

A cDNA encoding a G-protein-coupled receptor was cloned from the central nervous system of the pond snail Lymnaea stagnalis. The predicted amino acid sequence of this cDNA most closely resembles the Drosophila tyramine/octopamine receptor, the Locusta tyramine receptor, and an octopamine receptor (Lym oa1) that we recently cloned from Lymnaea. After stable expression of the cDNA in HEK293 cells, we found that [3H]rauwolscine binds with high affinity to the receptor (KD = 6.2.10(-9) M). Octopamine appears to be the most potent naturally occurring agonist to displace the [3H]rauwolscine binding (Ki = 3.0.10(-7) M). Therefore, the receptor is considered to be an octopamine receptor and is consequently designated Lym oa2. The novel receptor shares little pharmacological resemblance with Lym oa1, indicating that the two receptors represent different octopamine receptor subfamilies. Octopaminergic stimulation of Lym oa2 does not induce changes in intracellular concentrations of cAMP or inositol phosphates. However, electrophysiological experiments indicate that octopamine is able to activate a voltage-independent Cl- current in HEK293 cells stably expressing Lym oa2. Although opening of this chloride channel most probably does not require the activation of either protein kinase A or C, it can be blocked by inhibition of protein phosphorylation.

Heat-shock inactivation of the TFIIH-associated kinase and change in the phosphorylation sites on the C-terminal domain of RNA polymerase II

The C-terminal domain (CTD) of the RNA polymerase II largest subunit (RPB1) plays a central role in transcription. The CTD is unphosphorylated when the polymerase assembles into a preinitiation complex of transcription and becomes heavily phosphorylated during promoter clearance and entry into elongation of transcription. A kinase associated to the general transcription factor TFIIH, in the preinitiation complex, phosphorylates the CTD. The TFIIH-associated CTD kinase activity was found to decrease in extracts from heat-shocked HeLa cells compared to unstressed cells. This loss of activity correlated with a decreased solubility of the TFIIH factor. The TFIIH-kinase impairment during heat-shock was accompanied by the disappearance of a particular phosphoepitope (CC-3) on the RPB1 subunit. The CC-3 epitope was localized on the C-terminal end of the CTD and generated in vitro when the RPB1 subunit was phosphorylated by the TFIIH-associated kinase but not by another CTD kinase such as MAP kinase. In apparent discrepancy, the overall RPB1 subunit phosphorylation increased during heat-shock. The decreased activity in vivo of the TFIIH kinase might be compensated by a stress-activated CTD kinase such as MAP kinase. These results also suggest that heat-shock gene transcription may have a weak requirement for TFIIH kinase activity.

A phase I pilot study of pelvic radiation and alpha-2A interferon in patients with locally advanced or recurrent rectal cancer

PURPOSE

The purpose of this pilot study was to determine the maximum tolerated dose of alpha-2a interferon given by subcutaneous injection and combined with high dose pelvic radiation for locally advanced or recurrent rectal cancer.

METHODS AND MATERIALS

In this Phase I pilot study, patients with locally advanced, unresectable, or recurrent rectal cancer with or without distant metastases received external beam pelvic radiotherapy over 5 to 6 weeks combined with escalating doses of alpha-2a interferon. Interferon was escalated in increments of 3 million units for each patient cohort, starting at 3 million units subcutaneously 3 days weekly during pelvic radiation. Radiotherapy consisted of 44 Gy (2 Gy fractions) to the pelvis followed by a boost of 6 Gy or 16 Gy to gross pelvic tumor, depending on the presence or absence of small bowel in the boost field, respectively. Between 1991 and 1993, 10 patients were treated on this study, five with locally advanced and five with locally recurrent rectal cancer.

RESULTS

At 6 million units of interferon, Grade 3 (WHO criteria) toxicities were as follows: diarrhea (one), leukopenia (one), and neutropenia (one). One patient died of a massive GI bleed at this dose level. Death was not felt to be treatment related. The maximum tolerated dose of interferon was 3 million units three times weekly with radiation. Three patients had unusual complications at 4, 6, and 6 months possibly related to treatment. The first had a right distal ureteric stricture with a right urinoma. The second had a sudden left foot drop that has remained stable. The third had sudden onset of bilateral lower extremity paraplegia with spontaneous resolution.

CONCLUSIONS

The maximally tolerated dose of interferon alpha-2a given three times weekly during pelvic radiation was 3 million units based on acute side effects. Nevertheless, even at this dose level there were three unusual subacute complications possibly related to treatment. Caution is advised when combining interferon alpha-2a with high dose pelvic radiation, especially in patients with predisposing conditions (such as diabetes) for radiotherapy complications.

The nuclear matrix protein p255 is a highly phosphorylated form of RNA polymerase II largest subunit which associates with spliceosomes

The monoclonal antibody CC-3 recognizes a phosphodependent epitope on a 255 kDa nuclear matrix protein (p255) recently shown to associate with splicing complexes as part of the [U4/U6.U5] tri-snRNP particle [Chabot et al. (1995) Nucleic Acids Res. 23, 3206-3213]. In mouse and Drosophila cultured cells the electrophoretic mobility of p255, faster in the latter species, was identical to that of the hyperphosphorylated form of RNA polymerase II largest subunit (IIo). The CC-3 immunoreactivity of p255 was abolished by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole, which is known to cause the dephosphorylation of the C-terminal domain of subunit IIo by inhibiting the TFIIH-associated kinase. The identity of p255 was confirmed by showing that CC-3-immunoprecipitated p255 was recognized by POL3/3 and 8WG16, two antibodies specific to RNA polymerase II largest subunit. Lastly, the recovery of RNA polymerase II largest subunit from HeLa splicing mixtures was compromised by EDTA, which prevents the interaction of p255 with splicing complexes and inhibits splicing. Our results indicate that p255 represents a highly phosphorylated form of RNA polymerase II largest subunit physically associated with spliceosomes and possibly involved in coupling transcription to RNA processing.

Phase II study of ZD1694 in patients with advanced gastric cancer

ZD1694 (Tomudex), a quinazoline folate analogue, is a potent and selective thymidylate synthase inhibitor. A phase II trial was undertaken to determine the efficacy and toxicity of ZD1694 in patients with advanced, measurable gastric adenocarcinoma. ZD1694, 3.0 mg/m2, was administered as a 15 min intravenous infusion every three weeks. Tumor measurements were obtained for response assessment every six weeks. Clinical examinations, adverse event assessments, and clinical laboratory tests were performed every three weeks. Thirty-three patients were enrolled. There were no objective responses to ZD1694. In general, treatment was well-tolerated. Grade 3 and 4 toxicities were infrequent, and included mucositis, nausea and vomiting, leukopenia, thrombocytopenia, and elevations of liver enzymes. Mild to moderate asthenia was common. Toxicities with ZD1694 were reversible and manageable. In conclusion, ZD1694 has an acceptable toxicity profile but shows no antitumor activity in patients with advanced gastric cancer.

HSP27 locus cosegregates with left ventricular mass independently of blood pressure

Left ventricular hypertrophy remains a significant clinical problem and a predictor of fatal outcome in hypertension. Blood pressure per se and environmental modifiers including stress affect cardiac mass. Heat shock proteins are involved in the stress response as well as in the regulation of cardiac growth and cytoprotection. The present study evaluates heat shock protein 27 as a locus marker or candidate gene of cardiac hypertrophy in hypertension. The spontaneously hypertensive rat allele of heat shock protein 27 was associated with about a 6% increase in relative left ventricular weight (P = .0112) in 30 recombinant inbred strains from crosses of Brown Norway and spontaneously hypertensive rats. In 336 F2 crosses of spontaneously hypertensive and Wistar-Kyoto rats, the hypertensive allele was dominant and cosegregated with a similar 6% increase in the ratio of left ventricular weight to body weight (P = .0058) in rats fed a normal salt diet, but its contribution to left ventricular weight decreased in rats kept on a high salt diet. The contribution of the heat shock protein 27 allele was independent of blood pressure. We suggest that heat shock protein 27 represents a candidate gene/locus marker of cardiac hypertrophy in hypertension.

Analysis of quantitative trait loci for blood pressure on rat chromosomes 2 and 13. Age-related differences in effect

Previous studies have suggested the presence of quantitative trait loci (QTLs) influencing blood pressure on rat chromosomes 2 and 13. In this study, we mapped the QTLs in F2 rats derived from a cross of the spontaneously hypertensive rat and the Wistar-Kyoto rat and analyzed the effect of the QTLs on blood pressures measured longitudinally between 12 and 25 weeks of age. We analyzed 16 polymorphic markers spanning 147.3 cM on chromosome 2 and 13 markers spanning 91.6 cM on chromosome 13. Both chromosomes contained QTLs with highly significant effects on blood pressure (peak logarithm of the odds [LOD] scores, 5.64 and 5.75, respectively). On chromosome 2, the peak was localized to a position at anonymous marker D2Wox7, 2.9 cM away from the gene for the sodium-potassium ATPase alpha 1-subunit. On chromosome 13, the major peak coincided with the marker D13Mit2, 21.7 cM away from the renin gene, but there was a suggestion of multiple peaks. The effect of the QTL on chromosome 2 was seen throughout from 12 to 25 weeks of age, whereas interestingly, the effect for the QTL on chromosome 13 was maximal at 20 weeks of age but disappeared at 25 weeks of age, presumably because of the effect of either epistatic factors or environmental influences. The findings provide important information on QTLs influencing blood pressure on rat chromosomes 2 and 13 that will be useful in localizing and identifying the causative genes and emphasize the importance of age being taken into account when the effects of individual QTLs on a trait that shows significant age-related changes are being analyzed.

Connective tissue disease due to intentional inhalation of scouring powder

There have been reports in the literature of acute and chronic silicosis and connective tissue disease induced by occupational exposure to silica in factories producing scouring powder. Reports of connective tissue diseases induced by intentional inhalation of such a powder are rare and perhaps underestimated. We report the case of a young woman who developed Sharp's syndrome 5 yrs after diagnosis of acute silicosis due to scouring powder inhalation. The frequency of diseases from scouring powder as well as physiopathological and therapeutical issues of the association of pneumoconiosis and connective tissue disease are discussed.

Remodeling of the cytoskeletal lattice in denervated skeletal muscle

The effect of denervation-induced atrophy on the cytoskeletal lattice in rat fast- and slow-twitch skeletal muscle has been investigated. Immunochemical analyses and immunofluorescence microscopy experiments employing monospecific antibodies to dystrophin, desmin, and alpha-tubulin were carried out on intact and denervated muscles. The relative cellular content of dystrophin and desmin were reduced in the soleus muscle (slow-twitch), while significant increases were shown in the gastrocnemius muscle (fast-twitch). In both muscles, alpha-tubulin levels increased up to 12-fold as a function of time compared to control values. Immunofluorescence microscopy revealed a distinct rearrangement of the microtubule network toward a predominantly longitudinal alignment, which was accompanied by an increase in the density of the fluorescence. It is concluded that the relative increase of the three structural proteins in the fast-twitch gastrocnemius muscle may be related to the apparent resistance of this muscle type to denervation-induced atrophy. The increased alpha-tubulin content in denervated slow- and fast-twitch muscles could be indicative of an adaptive mechanism designed to maintain the integrity of the muscle fiber in view of eventual regenerative activities.

Renin secretion in conscious Lyon hypertensive rats

To characterize the renin secretory profile in Lyon hypertensive (LH) rats, renin responses to reductions of arterial pressure and beta-adrenoceptor stimulation were assessed in conscious unrestrained LH (n = 13) and Lyon normotensive (LN, n = 14) rats under normal-salt diet. Mean arterial pressure (MAP) in the infrarenal aorta was recorded beat to beat for 3 h. Then, plasma renin concentration (PRC) was measured 1) in basal conditions, 2) during 10-mmHg stepwise reductions of MAP down to 60 mmHg using a chronically implanted aortic inflatable cuff, and 3) during isoprenaline infusion (62.5, 125, and 250 ng.kg-1.min-1 iv). Compared with LN, LH rats had an elevated MAP (146 +/- 3 vs. 111 +/- 1 mmHg, P < 0.001) and decreased PRC [4.2 +/- 0.6 vs. 8.2 +/- 0.8 ng angiotensin (ANG) I.ml-1.h-1, P < 0.001] and kidney renin content (216 +/- 14 vs. 1,149 +/- 103 micrograms ANG I.h-1.g-1, P < 0.001). Pressure-dependent renin release occurred below 90 mmHg in LN rats and below 80 mmHg in LH rats, and its sensitivity in the low-pressure range did not differ between strains. Isoprenaline-induced increases in PRC were weaker (P < 0.01) in LH than in LN rats. In additional LH and LN rats (n = 6-8), acute ANG II AT1-receptor blockade with losartan (20 mg/kg, followed by 10 mg.kg-1.h-1 iv for 2 h) induced lesser (P < 0.001) PRC increases in LH than in LN rats. Renin responses to isoprenaline remained blunted (P < 0.01) during losartan infusion in LH rats. We conclude that, in LH rats, renin secretion is independent of MAP in the range of its spontaneous variations and is poorly responsive to beta-adrenoceptor stimulation, the alteration of which cannot be explained by an enhanced feedback inhibition by ANG II.

Elevated epidermal growth factor receptor levels in hypertensive Lyon rat kidney and aorta

1. The adult spontaneously hypertensive Lyon rats (LH strain) exhibited increased maximal epidermal growth factor (EGF) binding in freshly prepared kidney and aortic tissue membranes compared with age-matched normotensive (LN) or hypotensive (LL) strains. However, the binding affinity of the receptors to EGF was the same in all the three strains studied. These findings indicate an increased number of EGF receptors (EGFR) in the hypertensive LH strain. 2. Protein tyrosine kinase activity associated with the EGFR was also elevated in the LH strain compared with LN or LL strains, indicating that these receptors are functionally active. 3. There was a correlation between maximal EGF binding by aortic membranes and blood pressure in individual animals (r = 0.55; P < 0.001). 4. Taken together with previously reported similar findings in other models of genetic hypertension, the present results suggest a possible role for increased levels of EGFR in the development and maintenance of genetic hypertension.

[Two strains of genetically hypertensive rats, LH and SRH, have distinct profiles of postnatal expression of tropoelastin and type III collagen in the aortic wall]

Experimental pharmacology and studies on hypertension frequently use genetically hypertensive animal models like the SHR or the Lyon hypertensive rat LH. In order to further characterize these two models we measured the expression levels of three major extracellular matrix components in the aortic wall, tropoelastin (TE) and type I and type III collagen, during postnatal development. The type I collagen expression decreases progressively during the first twelve weeks of postnatal development without significant differences between SHR and LH, or their normotensive controls, WKY or LN respectively. No differences were detected either for the expression levels of TE and type III collagen between the hypertensive strains and their respective controls. However, direct comparison of the two hypertensive strains SHR and LH, revealed a specific, strong increase of TE and type III expression for the LH at 5 and 12 weeks (p < 0.001 and 0.005 respectively). The evolution of the ratios of expression levels between the two collagens (type III/type I) on one side and of TE and collagen type I (TE/type I) on the other side were similar for the hypertensive strains and their respective controls, but diverged significantly for LH and SHR animals (up to p < 0.001 depending on the age group). Both indicators, III/I and TE/I, are considerably higher in LH compared to SHR from 5 weeks of postnatal development onwards. Our results indicate that the genes for TE and type I and III collagen are regulated during postnatal development of LH and SHR. It is however not possible at this point to establish a link between mRNA levels and hypertension in these animals. Nevertheless, the ratios III/I and TE/I seem to be good phenotypic markers for the characterisation of LH and SHR strains.

New prolyl endopeptidase inhibitors: in vitro and in vivo activities of azabicyclo[2.2.2]octane, azabicyclo[2.2.1]heptane, and perhydroindole derivatives

A series of potent and selective prolylendopeptidase (PEP) inhibitors of the alpha-keto heterocyclic type has been obtained by replacing the classical central proline of 1-[1-(4-phenylbutanoyl)-L-prolyl]pyrrolidine (SUAM 1221,3) by non-natural amino acids PHI, ABO, and ABH. These 4-phenylbutanoyl side-chain-containing inhibitors exhibited potent in vitro inhibitory potencies with IC50 around 30 nM (compounds 24 and 25). Modulation of the side chain by replacement of the terminal phenyl ring by the dicyclopropyl moiety afforded derivatives 30 and 32 with improved potencies (IC50 between 10 and 20 nM). Furthermore, replacing the linear 4-phenylbutanoyl side chain by the (2-phenylcyclopropyl)carbonyl entity provided potent inhibitors with IC50 culminating at 0.9 nM on a rat cortex enzymatic preparation (compound 70). The configuration of the cyclopropyl ring had to be R,R in order to obtain not only a strong PEP inhibition in vitro but also a good activity in vivo, exemplified by inhibitor 68, which gave ID50 ip and po of 0.3 and 1 mg/kg, respectively. Finally, demonstration of the cognition-enhancing properties of compound 54 was given in the passive avoidance test using scopolamine-induced amnesia in the rat, where it dose dependently inhibited the scopolamine-induced decrease in avoidance response.

Conformational transitions within the calmodulin-binding site of Bordetella pertussis adenylate cyclase studied by time-resolved fluorescence of Trp242 and circular dichroism

The sequence situated around Trp242 in Bordetella pertussis adenylate cyclase, a bifunctional protein of 1706 amino acid residues, forms the core of the calmodulin-binding site. Peptides varying in size and in affinity for calmodulin, and preserving the same sequence around Trp242 were analyzed by time-resolved fluorescence spectroscopy. Their dynamic properties were compared to those of the catalytic domain of B. pertussis adenylate cyclase corresponding to the first 400 amino acid residues of the protein and in which the Trp69 residue was replaced by Phe. The heterogeneity of the fluorescence intensity decays of Trp242 is likely due to the existence of conformers in equilibrium as is suggested by the effect of trifluoroethanol both on the secondary structure content and the lifetime distributions. Binding to calmodulin leads to striking effects on the lifetime distribution profiles by selecting a major excited state population and therefore one major conformer. Trp242 still presents some degree of rotational freedom in the complexes. The reduction of rotational freedom is more important for the shorter peptides than for the longest one. A similar selection of one major conformer with the same lifetime was also observed for the Trp242 in the mutant protein when bound to calmodulin, as in the complexes with the peptides. We conclude that the site of interaction of B. pertussis adenylate cyclase with calmodulin has similar conformational flexibility as that evidenced in the isolated peptides. This property of the molecule allows a better adjustment of the enzyme upon interaction with calmodulin.

Dobutamine-induced wall motion abnormalities: correlations with myocardial fractional flow reserve and quantitative coronary angiography

OBJECTIVES

This study evaluated both the relation between dobutamine-induced wall motion abnormalities and the physiologic and morphologic features of epicardial coronary artery stenoses and the impact of the extent of the area at risk on the sensitivity of dobutamine echocardiography.

BACKGROUND

The accuracy of dobutamine echocardiography has traditionally been assessed by comparing results with stenosis geometry. Myocardial fractional flow reserve is a functional index of coronary stenosis severity that takes into account both antero-grade and collateral flow and may therefore be a more appropriate standard for comparison.

METHODS

Seventy-five patients with normal left ventricular function, good echocardiographic images and an isolated coronary stenosis underwent, within 6 h, dobutamine echocardiography, quantitative coronary angiography and intracoronary pressure measurements. Myocardial fractional flow reserve was calculated as the ratio of mean hyperemic distal coronary to aortic pressure.

RESULTS

The degree of dobutamine-induced dyssynergy correlated significantly with percent diameter stenosis (r = 0.68), area stenosis (r = 0.68) and minimal lumen diameter (r = -0.60) and markedly better with myocardial fractional flow reserve (r = -0.77). However, marked dispersion of the individual data was observed. The sensitivity of dobutamine echocardiography in detecting lesions with a minimal lumen diameter < or = 1 mm and diameter stenosis > or = 50% was 83% and 80%, respectively. All but one patient with a myocardial fractional flow reserve >0.75 had a normal stress test result. Among patients with a myocardial fractional flow reserve < or = 0.75, the sensitivity of dobutamine echocardiography was significantly lower for lesions in vessels with a reference diameter < or = 2.6 mm than for lesions in larger vessels (58% vs. 90%, p = 0.008).

CONCLUSIONS

1) The magnitude of wall motion abnormalities induced by dobutamine infusion correlates with angiographic and, more closely, with functional indexes of stenosis severity, even though a wide scatter is observed. 2) In patients with a functionally significant stenosis, the amount of myocardium at risk is a critical determinant of the accuracy of dobutamine echocardiography.

Major cardiovascular risk factors in Lyon hypertensive rats. A correlation analysis in a segregating population

OBJECTIVE

To investigate the association of blood pressure with the other major cardiovascular risk factors in a large population of back-cross to Lyon hypertensive (LH) rats.

METHODS

Mean arterial pressure was recorded in male freely moving Lyon normotensive (LN), LH, F1 and backcross to LH rats aged 30 weeks. Plasma cholesterol, triglycerides, insulin, creatinine, urea, fibrinogen and haematocrit levels, and the insulin: glucose ratio were measured in 31-week-old rats and 24h albuminuria in 6-week-old rats.

RESULTS

Adult LH rats exhibited a significant increase in plasma lipids, insulin, fibrinogen, creatinine, urea and haematocrit levels compared with LN rats. In young LH rats, at an age at which blood pressure is slightly increased, albuminuria was increased to a greater extent than expected from their blood pressure levels. In the adult back-cross to LH rats, only the plasma cholesterol level was associated with blood pressure. Moreover, the plasma cholesterol level was related to fibrinogen and haematocrit levels. Finally, in the same rats, albuminuria developed early in life was positively related to hypercholinesterolaemia measured later in life.

CONCLUSION

Plasma cholesterol, fibrinogen, haematocrit levels and early albuminuria could act synergistically in the enhancement or the development, or both, of vascular and kidney damage in the LH rat. Most interestingly, the association between plasma cholesterol level and blood pressure indicates that, as in essential hypertension, hypercholesterolaemia is a major phenotype associated with hypertension in the LH rat.

Left ventricular weight but not blood pressure is associated with sex chromosomes in Lyon rats

OBJECTIVE

To investigate, by studying reciprocal back-crosses to Lyon hypertensive (LH) rats, the involvement of sex chromosome loci in high blood pressure and heart weight in LH rats.

METHODS

Reciprocal F1 and F'1 generation male rats obtained from male LH x female Lyon normotensive (LN) and male LN x female LH crosses respectively, male back-cross rats obtained from male LH x female F1 or F'1 and from male F1 or F'1 x female LH crosses, and parental LH and LN male rats were studied at 29-31 weeks of age. Systolic, diastolic, mean and pulse pressures were measured beat to beat in unrestrained rats for 1 h. In addition, relative left and right ventricular weights were measured.

RESULTS

The average blood pressures did not differ between F1 and F'1 rats or between the four populations of back-cross rats. On the contrary, the relative left ventricular weight was higher in F'1 than in F1 rats. As a role for loci on the Y chromosome could be discarded by comparison of the two populations of back-cross rats, which differ only in the origin of their Y chromosome, this increase in the relative left ventricular weight of F'1 rats was consistent with an effect of a locus on the LH X chromosome. This was supported by findings in the back-cross populations, those populations in which 100% of the rats carried an LH X chromosome having a significantly higher left ventricular weight than those in which only 50% of the rats carried such a chromosome. The estimate of the genetic determination was higher for left ventricular weight (41%) than for mean arterial pressure (19%). Although these two parameters were associated in the back-cross population, the origin of the X chromosome had no influence on this association.

CONCLUSIONS

These findings indicate that, against the genetic background provided by the cross studied and at the age studied, the sex chromosomes of LH and LN rats do not contain loci at which alleles differentially influence blood pressure. They do, however, suggest that relative left ventricular weight in this model has a specific genetic determination, partly contributed by a locus on the X chromosome.

Phase II trial of ZD1694 (Tomudex) in patients with advanced pancreatic cancer

BACKGROUND

Currently available therapies for advanced pancreatic cancer offer only palliative benefits, and patients with this disease have a poor prognosis. We undertook a phase II trial of ZD1694 (Tomudex), a quinazoline folate analogue that is a potent and selective thymidylate synthase inhibitor, to determine this analogue's efficacy and safety in patients with advanced pancreatic adenocarcinoma.

PATIENTS AND METHODS

ZD1694, 3.0 mg/m2, was administered to 42 adult patients with pancreatic adenocarcinoma as a 15-minute intravenous infusion every 3 weeks for up to 6 doses. Objective tumor response was assessed every 6 weeks; clinical examinations, adverse event assessments, and clinical laboratory tests were performed every 3 weeks.

RESULTS

ZD1694 produced an overall response rate of 5% (95% confidence limits [CI], 1% to 16%) in the study group. Of 42 patients, 2 (5%) had a partial response, 12 (29%) had stable disease, 21 (50%) had disease progression, and 5 (11%) could not be evaluated for response. Grade 3 vomiting, grades 3 and 4 fever, grade 3 leukopenia, grade 4 thrombocytopenia, and grades 3 and 4 liver function elevations were reported. Toxic effects with ZD1694 were reversible and manageable.

CONCLUSIONS

ZD1694 has an acceptable safety profile but limited activity in patients with advanced pancreatic cancer.

A pilot study of the biologic and therapeutic effects of granulocyte colony-stimulating factor (filgrastim) in patients with acute myelogenous leukemia

In a carefully monitored pilot study, the in vivo biologic effects of filgrastim were investigated in eight patients with relapsed/refractory acute myelogenous leukemia. Within each patient, filgrastim was administered as a single agent prior to any chemotherapy in escalating doses of 0.12-6.0 micrograms/kg/day as a continuous intravenous infusion. The dose was increased every 14 days until an ANC of > or = 2500/mm3 had been achieved or there was evidence of proliferation of the leukemia. In patients who demonstrated growth of the leukemic clone, cytosine arabinoside was initiated at 200 mg/m2/day for 5 days. Through-out the course of therapy, the effects of filgrastim on maturation and proliferation were assessed by in vitro studies of bone marrow aspirates. Three patients demonstrated a sustained increase in ANC; one achieved a partial remission and remained on therapy for 31 weeks. Two of the three responding patients had hypocellular marrows at the time of initiating filgrastim and demonstrated a low but normal pattern of growth in CFU-GM assay early in the treatment course. This suggested that these two characteristics may define an environment in which filgrastim can induce a growth advantage for the normal residual hematopoietic elements. In this study of selected patients, filgrastim appeared safe.

Arrest at the G2/M transition of the cell cycle by protein-tyrosine phosphatase inhibition: studies on a neuronal and a glial cell line

The addition of the peroxovanadium (pV) derivatives potassium bisperoxo(1,10-phenanthroline)oxovanadate(v) (bpV[phen]) or potassium bisperoxo(pyridine-2-carboxylato) oxovanadate(v) (bpV[pic]), both of which are potent inhibitors of protein tyrosine phosphatases (PTPs) [Posner et al. (1994): J Biol Chem 269:4596-4604], to the culture medium of neuroblastoma NB 41 and glioma C6 cells resulted in a marked decrease in their proliferation rates and a progressive accumulation at the G2/M transition of the cell cycle. The effect was dependent on dose, cell type, and a pV compound employed. Mean values of the RNA-to-DNA and RNA-to-protein ratios in NB cells treated for 48 h with increased doses of bpV[phen] showed that general synthetic functions were not altered, nor did we observe oxidative damage to DNA using a sensitive DNA-nick detection assay. No changes in the expression and localization of vimentin, a component of the intermediate filament cytoskeleton, were observed by indirect immunofluorescence, showing that treatment did not disturb the cytoskeleton network. Measurements of BrdU incorporation into newly synthesized DNA showed that cells treated were not totally arrested. Furthermore, cells arrested G2/M were able to reenter the cycle rapidly after the release of inhibition. This progressive accumulation of G2/M coincided with the detection of tyrosine-phosphorylated p34cdc2 and a dramatic reduction in its kinase activity toward histone H1 by 48 h of culture. Both compounds were equally potent in inhibiting the catalytic activity of a yeast and the structurally distant mouse cdc25B in vitro, suggesting that augmented tyrosine phosphorylation of p34cdc2 derived from the in vivo inhibition of cdc25. Their equal in vitro potency contrasted with the considerably greater potency of bpV[phen] in vivo, in vivo suggesting that factors regulating the intracellular access of these compounds to cdc25 might be critical in determining in vivo specificity. In conclusion the final consequence of long-term exposure to potent and structurally defined PTP inhibitors on two highly proliferative nerve cell lines is to restrict cell growth. The corresponding hyperphosphorylation and reduced activity of p34cdc2 likely reflects the unusual sensitivity of cdc25 as an in vivo target for peroxovanadium compounds.

Purification of developmentally regulated avian 400-kDa intermediate filament associated protein. Molecular interactions with intermediate filament proteins and other cytoskeleton components

IFAPa-400, a 400-kDa developmentally regulated protein thought to be associated with intermediate filaments, has been purified from chick embryo hearts to investigate its interaction with vimentin and other IF proteins and to identify other cellular components to which this cytoskeletal protein associates. Previous studies suggested that this protein was associated with the vimentin-containing intermediate filament lattice of myoblasts and neuroblasts before their terminal differentiation, providing these cells with a particular intermediate filament cytoskeleton that could satisfy specific mechanical requirements during their intense morphogenetic activities. Although IFAPa-400 partially reassociated with vimentin and desmin in disassembly-reassembly experiments using crude IF preparations from chick embryo hearts, in vitro recombination of purified IFAPa-400 with vimentin and desmin failed to demonstrate any direct association. When purified IFAPa-400 was used as a probe in blot overlay assays, however, specific binding to vimentin and desmin was observed, providing the first evidence of a physical association between IFAPa-400 and intermediate filament proteins. The blot overlay experiments also demonstrated that IFAPa-400 binds to two unidentified polypeptides of 19 and 32 kDa. These results are thus consistent with the hypothesis that a structural lattice requiring a vimentin-IFAPa-400 combination constitutes the intermediate filament system of myogenic and neurogenic cells.

Survey of carer satisfaction with the quality of care delivered to in-patients suffering from dementia

Quality assurance in British National Health Service provision stresses the importance of taking account of the consumer's viewpoint. Elderly patients with dementia are not always able to contribute usefully to satisfaction surveys. Therefore, their careers' views were sought in order to assess the quality of services offered to this client group. Forty-one careers of patients discharged from the eight wards for the elderly mentally ill in Leicestershire, England, were randomly selected. Individual focused interviews were conducted in careers' own homes. Both quantitative and qualitative data were obtained by use of a questionnaire designed to tap the patients'/careers' experiences from pre-admission, through hospital stay to post-discharge. Interviews were asked to describe their favorable/unfavorable impressions of, and reactions to, all aspects of hospital care. These interviews were tape-recorded. Analysis of the data included quantitative measurements of scale ratings. Grounded theory was used to analyse qualitative data. A wealth of information was uncovered using this research technique. Much that was positive about the service was elicited. However, careers highlighted areas where they felt the quality of care could be improved within all the foci discussed. Twenty-two recommendations for quality improvements in service provision were made in the report as a result of this survey.