De Madres a Madres: women building community coalitions for health

How one group of Hispanic women in Houston, Texas, built community coalitions for primary health care is chronicled from the perspectives of the women. We describe how they formed partnerships with community businesses, health and social service agencies, schools, and churches to develop an outreach network that enables pregnant women to obtain early prenatal care. These women's steps in coalition building are related to feminist theory, with an emphasis on group decision making, shared power for the empowerment of all, and the creation of an environment in which individual worth and dignity are enhanced and risk taking is encouraged and supported.

Gs alpha-dependent and -independent desensitisation of prostanoid IP receptor-activated adenylyl cyclase in NG108-15 cells

NG108-15 mouse neuroblastoma x rat glioma cells were treated with the prostanoid IP receptor agonist iloprost (1 microM) and the time course of changes in the levels of prostanoid IP receptors, adenylyl cyclase activity, and the alpha-subunit of the stimulatory guanine nucleotide binding regulatory protein, Gs, were measured. Incubation of cells with iloprost produced a biphasic time course of desensitisation of prostanoid IP receptor-activated adenylyl cyclase. Parallel analysis of iloprost-induced loss of membrane Gs alpha, NaF-stimulated adenylyl cyclase and [3H]iloprost binding suggested only monophasic curves, with t0.5 values similar to the initial phase of desensitisation of iloprost-stimulated adenylyl cyclase activity. This suggests that the loss of receptor and Gs alpha occur at the same time and account for the initial period of desensitisation due to iloprost pretreatment. Pretreatment of NG108-15 cells with cholera toxin produced a near complete loss of membrane-associated Gs alpha, but the loss of [3H]iloprost binding due to iloprost treatment was not affected by pretreatment with cholera toxin, suggesting that prostanoid IP receptors can be down-regulated in the absence of any coupling to Gs. The second phase of desensitisation of iloprost-stimulated adenylyl cyclase activity, during which there was no further change in NaF-stimulated adenylyl cyclase or in the membrane levels of Gs alpha, was not due to protein kinase A activation, since elevating intracellular cyclic AMP levels with forskolin did not subsequently decrease iloprost-stimulated adenylyl cyclase activity or [3H]iloprost binding. These results demonstrate that iloprost pretreatment of NG108-15 cells induces two distinct phases of desensitisation; an initial desensitisation due to concurrent loss of prostanoid IP receptors and Gs alpha, and then a further desensitisation by an as yet uncharacterized mechanism during which there is no further loss of Gs alpha.

Chronic ethanol reduces immunologically detectable Gq alpha/11 alpha in NG108-15 cells

Recent work has shown that chronic ethanol treatment inhibits receptor-stimulated phosphoinositide hydrolysis in NG108-15 cells and that ethanol exerts this effect primarily at the level of the guanine-nucleotide binding protein (G protein). Here we investigated the effects of ethanol exposure on the expression of Gq alpha/11 alpha, two highly homologous G protein alpha-subunits that have been implicated as regulators of phosphoinositidase C. Addition of ethanol (10-200 mM) to the culture medium for 48 h caused a concentration-dependent decrease in the immunologically detectable levels of Gq alpha/11 alpha. A small (approximately 15%) reduction in Gq alpha/11 alpha was observed after only 6 h of exposure to 200 mM ethanol, but membrane levels were reduced by 31% at 48 h. The ethanol-induced loss of Gq alpha/11 alpha was apparently independent of factors present in the foetal calf serum component of the culture medium. These results suggests that the decrease in receptor-mediated phosphoinositide hydrolysis following chronic ethanol treatment of NG108-15 cells may be mediated in part by a reduction in the membrane levels of Gq alpha/11 alpha.

Influence of implantable cardioverter-defibrillators on the long-term prognosis of survivors of out-of-hospital cardiac arrest

BACKGROUND

Survivors of out-of-hospital cardiac arrest not associated with acute myocardial infarction are at high risk for recurrent cardiac arrest and sudden cardiac death. The impact of the implantable cardioverter-defibrillator on long-term prognosis in these patients is uncertain.

METHODS AND RESULTS

Three hundred thirty-one survivors of out-of-hospital cardiac arrest (age, 56 +/- 13.7 years) underwent electrophysiologically guided therapy. Implantable defibrillators were placed in 150 patients (45.3%), and 181 patients (54.7%) received pharmacological and/or surgical therapy alone. Left ventricular ejection fraction was 35.2 +/- 16.6% in defibrillator recipients and 45.3 +/- 18.2% in nondefibrillator patients. Median patient follow-up was 24 months in the defibrillator group and 46 months in the nondefibrillator group. In a proportional hazards model, the independent predictors of total cardiac mortality were left ventricular ejection fraction of less than 0.40 (relative risk, 4.55; 95% confidence interval, 2.44 to 8.33; P = .0001), absence of an implantable defibrillator (relative risk, 2.70; confidence interval, 1.41 to 5.00; P = .017), and persistence of inducible sustained ventricular tachycardia (relative risk, 1.84; 95% confidence interval, 0.97 to 3.49; P = .045). The 1- and 5-year probabilities of survival free of cardiac mortality in patients with left ventricular ejection fraction of less than 0.40 were 94.3% and 69.6% with a defibrillator and 82.1% and 45.3% without a defibrillator, respectively. For patients with left ventricular ejection fraction of 0.40 or more, the 1- and 5-year probabilities of survival free of cardiac mortality were 97.7% and 94.6% with a defibrillator and 95.4% and 86.9% without a defibrillator, respectively.

CONCLUSIONS

In survivors of out-of-hospital cardiac arrest, the implantable defibrillator is associated with a reduction in cardiac mortality, particularly in patients with impaired left ventricular function.

Compliance of the respiratory system in newborn infants pre- and postsurfactant replacement therapy

Surfactant administration causes a rapid and dramatic improvement in gas exchange, but paradoxically, studies have failed to show an improvement in the mechanical properties of the lung. We have measured dynamic and static (passive flow-volume technique) compliance before and after a single dose of bovine lipid extract surfactant in 22 premature infants with RDS. This had no effect on the measured dynamic compliance. In contrast, surfactant significantly increased static compliance from 0.41 +/- 0.02 to 0.55 +/- 0.04 mL/cm H2O/kg. This improvement was the result of a substantial recruitment of lung volume after surfactant administration. This led us to reduce ventilator pressures, which produced an increase in both dynamic and static compliance, but did not recruit additional volume. We conclude that surfactant causes a substantial increase in static compliance due to volume recruitment, which is consistent with reports of increase in the measured FRC. However, despite this improvement, the compliance is still below our normal range.

Pertussis toxin augments beta-adrenergic relaxation of muscarinic contraction in canine trachealis

We studied the effect of pertussis toxin (PT) and partial muscarinic antagonism using pirenzepine (PIR) on beta-adrenergic relaxation of muscarinic contraction in 188 tracheal smooth muscle (TSM) preparations from 25 dogs in vitro. Strips of TSM were incubated for 4 h at 37 degrees C in Krebs-Henseleit (K-H) perfusate with or without 10 micrograms/ml of PT. In tissues contracted to target tension (TT; 50% of maximal response to 127 mM potassium-substituted K-H [KCl]) with acetylcholine (ACh), pretreatment with PT decreased the concentration of isoproterenol (ISO) causing 30% relaxation from TT (RC30) from 1.3 +/- 0.8 x 10(-7) M (control) to 2.8 +/- 0.7 x 10(-8) M (p = 0.013). Pretreatment with PT also augmented the maximal relaxation elicited by 10(-5) M ISO. In separate studies, strips of TSM were contracted with ACh; pretreatment with 10(-7) M PIR decreased the concentration of ISO causing 50% relaxation (RC50) from 3.4 +/- 0.6 x 10(-7) to 9.6 +/- 1.5 x 10(-8) M (p = 0.042). Pretreatment with PIR did not affect relaxation elicited by ISO for strips contracted equivalently with KCl. In addition, PIR increased both the potency and efficacy of ISO in relaxing muscarinic contraction in sham-incubated strips of TSM but had no effect after incubation with PT. Neither PT nor PIR affected beta-adrenergic relaxation of TSM contracted with KCl. Our data demonstrate that beta-adrenergic receptor relaxation of muscarinic contraction is augmented by (1) incubation with PT and (2) partial blockade of muscarinic receptors.

Ethanol differentially regulates guanine nucleotide-binding protein alpha subunit expression in NG108-15 cells independently of extracellular adenosine

Recent work has suggested that chronic ethanol treatment induces heterologous desensitization of adenylate cyclase in a number of cell lines maintained in culture and that this phenomenon is mediated by adenosine. It has been proposed that ethanol induces the accumulation of extracellular adenosine, which then down-regulates the Gs alpha protein and leads to heterologous desensitization. Here we investigated the effects of chronic ethanol treatment on the expression of Gs alpha, Gi alpha, and Go alpha, as well as cAMP signal transduction, in NG108-15 cells and further examined the role of adenosine in mediating these effects. Pretreatment of NG108-15 cells with 200 mM ethanol for 2 days reduced membrane levels of Gs alpha and Gi alpha and increased those of Go alpha. However, ethanol did not reduce the levels of Gs alpha and Gi alpha 2 mRNA in these cells. The ability of ethanol to alter alpha subunit expression was not reversed by removal of extracellular adenosine and could not be mimicked by an adenosine agonist. Chronic ethanol treatment increased both basal and agonist-stimulated cAMP accumulation in NG108-15 cells. Whereas the increase in basal cAMP was abolished by acute addition of adenosine deaminase, the increase in agonist-stimulated cAMP accumulation was not. Morphological examination of the cells indicated that ethanol inhibited cell division and promoted the apparent differentiation of the cells. These results indicate that ethanol induces complex alterations in guanine nucleotide-binding protein alpha subunit expression and cAMP signal transduction in NG108-15 cells and that it is unlikely that these effects are mediated simply by adenosine.

The role of radiography and computed tomography in the diagnosis of acute dislocation of the proximal tibiofibular joint

A cadaveric study was undertaken to determine the best radiographic method of diagnosing dislocation of the proximal tibio-fibular (PTFJ) joint. Three pairs of cadaver knees were used, the right side serving as a control in each case. Plain radiographs, antero-posterior (AP) lateral and 45 degrees oblique films, and axial computed tomography (CT) scans were obtained with the joints in each of three positions: (1) anatomical, (2) dislocated anteriorly and (3) dislocated posteriorly. Similar views were obtained in the control joints with the PTFJ undisturbed. The radiographs were assessed by eight independent observers and the results were analysed. The diagnostic accuracy with plain AP and lateral radiographs was 72.5%. This was unchanged with the addition of oblique views, but improved to 82% with the control films and 86% with the axial CT scans. The authors conclude that in the diagnosis of suspected dislocation of the PTFJ, axial CT scanning is the investigation of choice. Plain AP, lateral and comparison views are useful but less accurate, while oblique views are unhelpful and unnecessary.

Community health organizing: whom are we empowering?

Current strategies for initiating and operating community health programs rely on one of two approaches. One is a predetermined, operational process. The other comes from the grassroots, beginning with involvement of the recipients of the program. This editorial chronicles how one grassroots program, begun by volunteer mothers and one community health nurse, developed into a partnership for primary health care that advocates and empowers the entire community. In the end, the editorial challenges community health organizers to ask whom their programs are empowering--the community or the organizers themselves?

Cloning of the gene coding for a human receptor for formyl peptides. Characterization of a promoter region and evidence for polymorphic expression

Recently we reported that, in HL-60 cells, transcription of the formyl peptide receptor (FPR) gene can be up- and downregulated by agents that induce differentiation of HL-60 cells into neutrophils. To begin studying the mechanisms involved in regulation of FPR gene expression, we cloned two human cDNAs and the gene coding for FPR. The genomic clone (pINF14) contained a 14.5-kb insert. A 2.7-kb EcoRI fragment was obtained from pINF14 that hybridized with an FPR open reading frame probe. The EcoRI fragment was sequenced and found to contain an intronless FPR open reading frame. Sequence alignment of the EcoRI genomic fragment with the FPR cDNA revealed that the first 31 bases of 5' untranslated FPR cDNA were not represented in the genomic fragment. Furthermore, a splicing consensus sequence was present in the genomic fragment at the site of divergence with the cDNA sequence. Restriction mapping and Southern blot analysis identified a 121-bp fragment that contained the sequence corresponding to the first 31 bases of 5' untranslated FPR cDNA. An additional (previously undescribed) 15-bp cDNA sequence in the 5' end of FPR were identified using an anchored polymerase chain reaction. This sequence was also contained in the genomic 121-bp fragment. This 121-bp fragment was located 5.2 kb (intron) upstream of the FPR open reading frame. It contained an unusual TATA box and displayed transcriptional activity in vitro and in vivo. Potential binding sites for AP-1 and glucocorticoid receptor were identified upstream of the putative TATA box.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning of a cDNA encoding a receptor related to the formyl peptide receptor of human neutrophils

We cloned a cDNA (RFP) encoding a receptor (RFP) related (70% overall nucleotide homology) to the formyl peptide receptor of human neutrophils (hFPR). RFP is a seven-transmembrane-domain receptor and its distribution is limited to myeloid cells. Domain sequence comparison with hFPR reveals highly conserved regions and provides clues to putative domains involved in ligand binding and receptor desensitization.

Cyclic AMP produces desensitization of prostacyclin and adenosine A2 receptors in hybrid cell lines but does not affect Gs function

Prostacyclin and adenosine A2 receptors stimulate adenylate cyclase activity in the related somatic hybrid cell lines NG108-15 and NCB20. The role of cAMP in the desensitization of these receptors has been examined. Pretreatment for 17 h with forskolin or 8-bromo-cAMP had the same effect in both cell lines. There was no change in the response to sodium fluoride or forskolin, suggesting that the function of Gs and adenylate cyclase were unaffected by increased levels of cAMP. Receptor responses were affected however; the maximum response to N-ethylcarboxamidoadenosine (an A2 receptor agonist) was reduced by 30-40%, there was a small but consistent shift to the right of the dose-response curve for iloprost (a stable analogue of prostacyclin) and [3H]iloprost binding studies revealed a loss of prostacyclin receptors. However, the loss of receptor responsiveness was much smaller than that which occurs following pretreatment with prostacyclin or adenosine A2 receptor agonists (Keen et al. (1989) Biochem. Pharmacol. 38, 3827-3833; Kelly et al. (1990) Br. J. Pharmacol. 99, 309-316) suggesting that cAMP may not play a major role in agonist mediated desensitization.

Prospective study of the quality of survival of infants with critical fetal reserve detected by antenatal cardiotocography

From 1981 to 1986 antenatal cardiotocographic monitoring was performed on 9,992 high-risk pregnancies selected from a total obstetrical population of 31,518 patients (31.7%). A critical fetal reserve pattern was detected in 89 patients (0.9%) whose pregnancies resulted in 68 surviving infants, 19 perinatal deaths and 2 sudden infant deaths. Since 47.4% of the infants who died in the perinatal period did so because of a related congenital malformation, such a defect should be excluded in the fetus with critical fetal reserve, by ultrasonography, before delivery (there is usually insufficient time for fetal karyotyping). Sixty-three (92.6%) of the surviving children were assessed at our Growth and Developmental Clinic and disabilities were detected in 16 (25.4%); however, the disability was major in only 5, including 2 children with Down syndrome. The quality of survival of infants born from pregnancies complicated by critical fetal reserve was satisfactory as 60 of 63 children (95.2%) had neither a major disability related to intrauterine hypoxia identified by the cardiotocographic pattern, or had one likely to significantly interfere with their quality of life. Our results suggest that pregnancies can be continued until the cardiotocographic pattern becomes critical in order to gain fetal maturity, without compromise to the fetal brain.

Regulation of formyl peptide receptor expression and its mRNA levels during differentiation of HL-60 cells

When incubated with N6-2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (dbcAMP), HL-60 cells expressed formyl peptide receptor (FPR) (as assessed by ligand binding) and FPR transcripts in a time- and concentration-dependent fashion. Experiments using dbcAMP analogs modified at either the C-6 or C-8 position indicated that the process was mediated by a protein kinase A type I, and protein kinase A type I activity was isolated from undifferentiated HL-60 cells by DEAE-Sephacel chromatography. Forskolin mimicked the effects of dbcAMP. Forskolin and dbcAMP-dependent expression of FPR and FPR transcript was inhibited by staurosporine. Retinoic acid (but not retinal or retinol) was capable of inhibiting dbcAMP-dependent expression of FPR mRNA half-life. Dexamethasone enhanced the effects of dbcAMP and blocked the inhibitory effect of retinoic acid on expression of FPR and FPR transcripts. Phorbol 12-myristate 13-acetate (PMA) alone (1.5-15 nM) failed to induce HL-60 to express FPR and FPR transcripts. Low concentrations (1.5 nM) of PMA enhanced the ability of dbcAMP to induce HL-60 cells to express FPR and FPR transcript, whereas high (15 nM) concentrations of PMA inhibited dbcAMP effects. These results indicate that expression of FPR and FPR transcripts by HL-60 cells can be up- and down-regulated by agents that induce HL-60 cells to differentiate and that a "cross-talk" effect exists between protein kinase A and protein kinase C that modulates FPR gene transcription (and receptor expression) by these cells.

Very low birth weight and growth to age 8 years. II: Head dimensions and intelligence

The occipitofrontal circumference was measured in all available children in the following cohorts at ages 2, 5, and 8 years: group 1, consisting of 79 children with birth weight between 500 and 999 g; group 2, with 111 children with birth weight between 1000 and 1499 g; and group 3 with 56 children with birth weight greater than 2500 g; all were white with no signs of moderate or severe cerebral palsy. National Center for Health Statistics reference values indicated substantially more children with an occipitofrontal circumference lower than the 10th percentile, particularly at age 2 years, compared with Nellhaus reference data. Occipitofrontal circumference was the head measurement best correlated with the Full Scale IQ on the Wechsler Intelligence Scale for Children-Revised. Dolichocephaly, often seen in very-low-birth-weight children was unrelated to IQ, and correction of occipitofrontal circumference for dolichocephaly was rarely of clinical importance.

Survivors of extreme prematurity--outcome at 8 years of age

Of 149 infants liveborn in a large maternity hospital in 1980 to 1982 and delivered between 24 and 29 completed weeks of gestation inclusive, 91 (61%) survived; 88 (97%) survivors were assessed at 8 years' corrected age; 77% of children were not disabled; disability was mild in 13%, moderate in 2% and severe in 4% of children. Although survival decreased with decreasing gestation, disability in survivors did not increase. An earlier assessment of the same children at approximately 2 years of age had been unduly pessimistic particularly for those born less than or equal to 26 weeks' gestation. The only other reports in the literature on outcome by gestation have all assessed the children in early childhood, and estimates of severe disability rates from these studies will probably also be too pessimistic. Since the rate of severe disabilities in infants of borderline viability is not much higher than in more mature infants the obstetrician should mainly consider survival chances for the fetus, and not be overly concerned with long-term neurological outcome, when making clinical decisions.

Extracellular Ca2+ mobilization in potential-dependent contraction of trachealis of maturing swine

We studied the effect of maturation on potassium-induced parasympathetic activation and Ca2+ entry in tracheal smooth muscle (TSM) from fifteen 2-wk-old (2ws) and sixteen 10-wk-old (10ws) male domestic farm swine. Atropine (10(-7) M) caused inhibition of the maximal contraction elicited by potassium to 50.3 +/- 2.6% maximum of control response (P less than 0.001) in TSM from 2ws but had no significant effect in TSM from 10ws (94.6 +/- 4.2% maximum; P = NS vs. control). Verapamil (10(-7) M) plus 10(-7) M atropine reduced contraction elicited by potassium in both 2ws (23.7 +/- 5.8% maximum; P less than 0.001 vs. control) and 10ws (50.6 +/- 6.3% maximum; P less than 0.001 vs. control, P less than 0.05 vs. 2ws); 10(-6)M verapamil caused greater than 95% blockade of contraction caused by potassium in both 2ws and 10ws. In separate studies, atropine-treated strips were equilibrated with extracellular Ca2+ concentrations ([Ca2+]o) ranging from normal (1X [Ca2+]o) to four times normal (4x [Ca2+]o). Increasing [Ca2+]o increased maximal contractile response in atropine-treated TSM strips from 68.7 +/- 3.8% maximum for 1x [Ca2+]o to 100.8 +/- 4.8% maximum for 4x [Ca2+]o (P less than 0.001) in 2ws. Neither atropine nor [Ca2+]o affected maximal responses of TSM in 10ws (103.5 +/- 3.0% maximum for 1x [Ca2+]o; P = NS vs. control). However, in the presence of atropine and verapamil, 4x [Ca2+]o augmented KCl-elicited contraction of TSM from both 2ws (46.9 +/- 6.3% maximum; P less than 0.01 vs. control) and 10ws (78.6 +/- 2.3% maximum; P less than 0.005 vs. control).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced activity of acetylcholinesterase in canine tracheal smooth muscle homogenates after active immune-sensitization

Previous investigations have suggested that immune-sensitization increases airway smooth muscle responsiveness to cholinomimetic stimulation by reducing the rate of degradation of acetylcholine. To examine the hypothesis that increased cholinomimetic responsiveness of tracheal smooth muscle (TSM) caused by immune-sensitization results from inhibition of acetylcholinesterase (AChase) activity, we developed a method for direct measurement of AChase activity in homogenates of TSM obtained from mongrel dogs actively sensitized in vivo to ragweed pollen extract (n = 7) and sham-sensitized littermate controls (n = 7). For both sensitized and control specimens, saturation of AChase was obtained at approximately 3.12 mM substrate (acetylthiocholine); however, maximal enzyme activity in homogenates of ragweed-sensitized tissues was significantly less (0.862 +/- 0.088 absorbance units/min/mg protein [AU/min/mg]) compared to control homogenates (1.590 +/- 0.129 AU/min/mg; P less than 0.001). Kinetic analysis (Eadie-Hofstee plot) indicated similar Michaelis constants (Km) for AChase from ragweed-sensitized (0.360 +/- 0.063) and control (0.336 +/- 0.062) homogenates (P = NS). The concentration of physostigmine eliciting half-maximal inhibition (Ki) of AChase activity also was similar for tissues from sensitized (-7.92 +/- 0.032 log M) and control animals (-7.86 +/- 0.012 log M; P = NS). Pretreatment with selected mediators of anaphylaxis (10(-4) M histamine, 10(-6) M serotonin, 10(-5) M prostaglandin E2, 10(-6) M prostaglandin F2 alpha, and 10(-7) M leukotriene D4) did not affect AChase activity. Our data demonstrate reduced AChase activity in homogenates of canine TSM after active immune-sensitization in vivo. This corresponds to functional augmentation of cholinomimetic contraction in actively sensitized tissues.

Guanine nucleotide sensitivity of [3H]iloprost binding to prostacyclin receptors

A component of the displaceable binding of the stable prostacyclin analogue, [3H]iloprost, to membranes from human platelets and the somatic hybrid cell lines NG108-15 and NCB20, was inhibited by guanine nucleotides. The order of potency of a range of nucleotides for this effect was GTP gamma S greater than GppNHp greater than GTP greater than GDP = GMP; ATP, UTP and CTP were ineffective at concentrations up to 1 mM. In the presence of 100 microM GppNHp, iloprost binding curves were displaced to the right of curves obtained in the absence of guanine nucleotide, and their Hill slopes were greater. This was consistent with a conversion of a minor population of high affinity agonist binding sites to lower affinity sites in the presence of guanine nucleotides. These effects of guanine nucleotides on the binding of the agonist ligand [3H]iloprost were consistent with an interaction with a G protein coupled receptor.

Changing two-year outcome of infants weighing 500 to 999 grams at birth: a hospital study

Survival and neurodevelopmental outcome to 2 years were determined for two cohorts of infants weighing 500 to 999 gm at birth, born in a tertiary maternity hospital. Live births increased over time from an annual average of 48.7 in the first era (January 1977 to March 1982) to 64.6 in the second era (January 1985 to December 1987), largely from referrals of additional mothers with pregnancy complications. In the first era, 33.6% (86/256) of infants survived to 2 years; the survival rate improved significantly to 45.9% (89/194) in era 2. After adjustment for birth weight, the odds ratio for survival in era 2 versus era 1 was 1.39 (95% confidence interval = 1.12, 1.73; p less than 0.01). One known survivor in each era was not seen at 2 years of age. In the first era, 59.3% (51/86) of 2-year-old children were free of disability compared with 68.5% (61/89) in era 2 (NS), but the Mental Development Index of the Bayley Scales improved significantly, from 90.0 in era 1 to 98.0 in era 2. For infants weighing less than 800 gm at birth, not only did the 2-year survival rate improve, adjusted for birth weight (odds ratio = 1.53; 95% confidence interval = 1.06, 2.20; p less than 0.05), but there was also a significant reduction in neurologic disabilities in survivors (p = 0.03). For infants weighing 800 to 999 gm at birth, there was a significant improvement in the survival rate, adjusted for birth weight (odds ratio = 1.37; 95% confidence interval = 1.04, 1.79; p less than 0.05), but the rate of neurologic disabilities was unchanged. Increased survival in our tertiary maternity center was achieved without increasing the annual number of severely disabled 2-year-old survivors.

Second twin: quality of survival if born by breech extraction following internal podalic version

The intrapartum management of the vertex-breech and vertex-transverse twin gestation is controversial. The fall in perinatal mortality rate to a low level has resulted in this parameter failing to be an adequate gauge of the safety of breech extraction and the answer lies in the quality of survival of the infants. Fifty-one twin pairs, collected over 12 years at the Mercy Hospital for Women, Melbourne, occurred where twin 2 was born by breech extraction following internal inversion and the control (twin 1) did not have this procedure performed. In 8 pairs either a stillbirth or neonatal death occurred; in one pair childhood death due to an accident (fire) occurred; in 4 pairs the parents refused entrance to the study as they perceived both twins to be similar; in 2 sets the assessment was incomplete; 11 sets were untraceable leaving 25 sets fully assessed as children ranging in age from 2 to 12 years. Growth, and psychological scores were not significantly different between twins 1 and 2 but 2 children had cerebral palsy and both were born by breech extraction following internal version at 29.2 and 30.1 weeks' gestation, respectively. Because of small numbers the results failed to achieve statistical significance and this study was unable to answer the question regarding the safety of breech extraction following internal version but did show that the majority of infants so born do well.

Defective polymorphonuclear leukocyte formyl peptide receptor(s) in juvenile periodontitis

Juvenile periodontitis (JP) is a disease characterized by severe gingival infections. PMN from some JP patients exhibit abnormal chemotactic responsiveness when challenged with the synthetic formyl peptide, FMLP. While investigating PMN function in JP, we found a patient in whom abnormal PMN chemotactic responses to FMLP were associated with a defective population of PMN formyl peptide receptor(s) (FPR). JP PMN failed to respond chemotactically when challenged with FMLP, but exhibited normal chemotactic responses upon exposure to purified human C5a. Furthermore, JP PMN were capable of degranulating and generating superoxide anion radicals as well as normal PMN upon exposure to FMLP. Binding studies demonstrated that JP PMN had a diminution in the number of high-affinity FPR. Studies in which FPR was radiolabeled by chemical cross-linking demonstrated that JP PMN FPR exhibited the same molecular weight and N-linked glycosylation as normal PMN FPR. JP PMN FPR, however, was more resistant to papain cleavage than normal PMN FPR. Autoradiograms obtained from 2D-PAGE of normal and JP PMN FPR demonstrated decreased amounts of FPR isoforms in JP PMN.

Effect of in vitro preconditioning on tracheal smooth muscle responsiveness

We evaluated the effect of preconditioning of the isometric contractile response of canine tracheal smooth muscle (TSM) in vitro. Strips of epithelium-free TSM (n = 90) were excised from 16 anesthetized dogs and fixed isometrically in tissue perfusion chambers. Experiments were performed using methods previously reported in which the following parameters were investigated: 1) quiescent equilibration time in the perfusion chamber (0-120 min); 2) effect of repeated exchange of perfusate; 3) method of determining the optimal resting length (Lmax) for presetting of resting tension (RT); 4) effect of precontraction during the equilibration phase on the contractile response to agonists administered subsequently; and 5) method of determining RT on the response to muscarinic stimulation. When other variables were uniform, neither equilibration time nor perfusate exchange affected potency or efficacy of the response generated subsequently to acetylcholine (ACh). However, both potency (range of EC50: -5.71 +/- 0.14 log M to -6.52 +/- 0.24 log M; P less than 0.02) and efficacy (range of maximal active tension: 1,143 +/- 268 g/cm2 to 2,878 +/- 151 g/cm2; P less than 0.001) of ACh were altered substantially as a result of the method used to estimate Lmax. Repeated precontraction by electrical field stimulation or with 127 mM KCl did not alter potency or efficacy of contraction elicited by ACh. Maximal active tension generated with 10(-3) M ACh was 2,878 +/- 151 g/cm2 after 12-15 tetanizing field stimulations and 2,696 +/- 198 g/cm2 after 5-7 contractions with 127 mM KCl (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Octimibate, a potent non-prostanoid inhibitor of platelet aggregation, acts via the prostacyclin receptor

1. Octimibate, 8-[(1,4,5-triphenyl-1H-imidazol-2-yl)oxy]octanoic acid, is reported to have antithrombotic properties. This is in addition to its antihyperlipidaemic effects which are due to inhibition of acylCoA:cholesterol acyltransferase (ACAT). The aim of this study was to investigate the mechanism of the antithrombotic effect of octimibate, and to determine whether the effects of octimibate are mediated through prostacyclin receptors. 2. In suspensions of washed (plasma-free) human platelets, octimibate is a potent inhibitor of aggregation; its IC50 is approx. 10 nM for inhibition of aggregation stimulated by several different agonists, including U46619 and ADP. The inhibitory effects of octimibate on aggregation are not competitive with the stimulatory agonist; the maximal response is suppressed but there is no obvious shift in potency of the agonist. In platelet-rich plasma, octimibate inhibits agonist-stimulated aggregation with an IC50 of approx. 200 nM. 3. Octimibate also inhibits agonist-stimulated rises in the cytosolic free calcium concentration, [Ca2+]i, in platelets. Both Ca2+ influx and release from intracellular stores are inhibited. The effects of octimibate on aggregation and [Ca2+]i are typical of agents that act via elevation of adenosine 3':5'-cyclic monophosphate (cyclic AMP). Similar effects are seen with forskolin, prostacyclin (PGl2) and iloprost (a stable PGl2 mimetic). 4. Octimibate increases cyclic AMP concentrations in platelets and increases the cyclic AMP-dependent protein kinase activity ratio. Octimibate stimulates adenylyl cyclase activity in human platelet membranes, with an EC50 of 200 nM. The maximal achievable activation of adenylyl cyclase by octimibate is 60% of that obtainable with iloprost. Octimibate has no effect on the cyclic GMP-inhibited phosphodiesterase (phosphodiesterase-ITI), which is the major cyclic AMP-degrading enzyme in human platelets.5. Octimibate inhibits, apparently competitively, the binding of [3H]-iloprost (a stable PGl2 mimetic) to platelet membranes; the estimated Ki is 150 nm. 6. The platelets of different species show considerable differences in the apparent potency of their inhibition of aggregation by octimibate; platelets from cynomolgus monkeys are 3 fold more sensitive than those from humans, while rat, cat and cow platelets are 50, 100, and 250 fold less sensitive than human platelets. The sensitivity of these different species to iloprost, however, varies over a range of only 10 fold with no obvious difference between primates and non-primates. 7. Octimibate appears to be a potent agonist (aggregation), or partial agonist (adenylyl cyclase), at prostacyclin receptors and is the first non-prostanoid agent of this type to be identified. The species differences in relative potency of octimibate and iloprost may reflect the existence of receptor subtypes.

Effect of phorbol myristate acetate on processing of formyl peptide receptors by human neutrophils

We examined the effect of phorbol myristate acetate on the ability of human neutrophils to process formyl peptide receptors. The receptor was affinity-labeled and its extracellular localization assessed over time, by cleavage of extracellular labeled receptor with papain. Neutrophils were capable of internalizing (and/or recycling) affinity labeled formyl peptide receptor in the absence of extracellular calcium. This phenomenon was dependent upon stimulation with phorbol myristate acetate, suggesting a role for protein kinase C in this process.

Effect of interleukin-1 on gamete interaction and mouse embryo development

Early stages of endometriosis have been shown to be associated with infertility. The pathophysiology of this relationship is unclear. To determine if interleukin-1 (IL-1), a peritoneal macrophage product, has any effect on gamete interaction and early embryo development, human recombinant IL-1 was added to the coincubation of gametes in the sperm penetration assay (SPA), human zona pellucida assay (ZPPA) and culture medium (Ham's F-10) used for processing semen samples with the layering method, with analysis of velocity and motility after 24 hours. IL-1 was also added to mouse embryos (two cells) cultured for 72 hours. The results showed that IL-1 caused impairment of SPA and ZPPA when compared to control medium, without significant alterations in sperm velocity and motility. Also, IL-1 demonstrated significant inhibition of mouse embryo development. These results help explain subfertility associated with early stages of endometriosis.

Maturation of acetylcholinesterase expression in tracheal smooth muscle contraction

We examined postganglionic development of acetylcholinesterase (AChase) activity and tracheal smooth muscle (TSM) contraction elicited by cholinomimetic activation and electrical field depolarization in vitro. Epithelium-intact tracheal strips excised from 21 2-wk-old swine (2ws) and 19 10-wk-old swine (10ws) were tethered isometrically at optimal resting length, and responses were expressed as percent of the maximum to 63 mM potassium-chloride (%KCl). Cumulative concentration-response curves to KCl were equivalent for TSM from 2 and 10ws. However, maximal contraction to ACh in 2ws (168 +/- 8.4 %KCl) was greater than for 10ws (142 +/- 2.3 %KCl; P less than 0.02). Stimulus-response curves (field electrodes; AC source) demonstrated greater sensitivity for TSM in 10ws (stimulus causing 50% of the maximal response = 3.32 +/- 0.13 V in 2ws vs. 2.25 +/- 0.12 V in 10ws; P less than 0.001), indicating that the greater cholinomimetic responsiveness of 2ws did not result from augmented presynaptic nerve conduction. The AChase inhibitor, physostigmine, caused 1) greater sensitivity of responses elicited by electrical field stimulation in 2ws (P less than 0.05) but not in 10ws (P = NS), 2) augmentation of maximal responses to exogenous ACh in 10ws (27% increase; P less than 0.01) but not 2ws (2% increase; P = NS), and 3) a greater increase in sensitivity to cholinomimetic activation in 2ws compared with 10ws (P less than 0.02). These data demonstrate increased cholinergic contraction of TSM in 2 vs. 10ws that results at least in part from reduced AChase activity in the trachea of immature animals.

NaF and guanine nucleotides modulate adenylate cyclase activity in NG108-15 cells by interacting with both Gs and Gi

1. NaF (10 mM) produced a 2-3 fold increase in adenylate cyclase activity in homogenates of NG108-15 cells incubated in the presence of 1 microM GTP. Higher concentrations of NaF suppressed adenylate cyclase activity. 2. In the presence of the adenosine receptor agonist 5'-(N-ethyl)-carboxamidoadenosine (NECA; 100 microM) or the prostacyclin receptor agonist iloprost (10 nM), NaF produced a much smaller increase in adenylate cyclase activity, whereas in the presence of a saturating concentration of iloprost (1 microM), NaF only inhibited adenylate cyclase activity. 3. Similarly, Gpp(NH)p activated basal adenylate cyclase activity, and inhibited 1 microM iloprost-activated enzyme activity. In the presence of 10 microM forskolin, NaF or Gpp(NH)p increased adenylate cyclase activity synergistically. Analysis of concentration-effect curves indicated that NaF (2 mM) or Gpp(NH)p (100 microM) increased the potency with which forskolin activated adenylate cyclase, whilst reducing the maximum activation of adenylate cyclase by iloprost. 4. Opiate receptors mediate inhibition of adenylate cyclase, and the opiate agonist morphine (100 microM) reduced the capacity of NaF or Gpp(NH)p to inhibit iloprost-activated adenylate cyclase. Unexpectedly, pertussis toxin treatment enhanced the ability of NaF or Gpp(NH)p to inhibit iloprost-activated adenylate cyclase. 5. In the absence of GTP, NaF and Gpp(NH)p remained able both to activate basal adenylate cyclase and to be synergistic with forskolin in activating the enzyme. In contrast the ability of NaF and Gpp(NH)p to inhibit iloprost-activated adenylate cyclase was substantially lost in the absence of added GTP. These results suggest that NaF modulates adenylate cyclase activity in NG108-15 cell membranes by interacting with the alpha subunits of both G0 and Gi regulatory proteins. The effects of NaF and Gpp(NH)p are critically dependent on the prior mode and extent of activation or inhibition of this transmembrane signalling pathway. This simple system may be of use in assessing alterations in GSO-O interaction following manipulations such as hormone receptor desensitization.

Bladder volume determination using a dedicated, portable ultrasound scanner

Urethral catheterization, the standard method for measurement of bladder volume, is associated with patient discomfort plus the risks of urethral trauma and urinary tract infection. A portable ultrasound instrument that automatically determines bladder volume was used for 164 determinations and the digital readout correlated with the catheterized volume (r2 equals 0.79). This instrument is a noninvasive alternative to urethral catheterization for the determination of bladder volume in most patients.

Changing diagnosis of cerebral palsy in very low birthweight children

The stability of the diagnosis of cerebral palsy from 2 to 5 years of age was examined in 83 children of birthweight under 1000 gm, and 112 of birthweight 1000 to 1500 gm. In 20 2-year-old children with cerebral palsy, the diagnosis persisted in 11 (55%, 95% confidence intervals 35.1 to 76.9%); 2 of 175 children (1.1%) free of cerebral palsy at 2 years of age subsequently developed the condition. Severe or moderate cerebral palsy at 2 years persisted in all eight children (100%). In 9 of 12 children in whom cerebral palsy at 2 years had disappeared by 5 years, minor neurologic abnormalities and left-hand preference occurred frequently but mean psychologic tests scores were similar to children always free of cerebral palsy. In this cohort, cerebral palsy at 2 years was not a static condition, but overestimated later prevalence.

Segregation of discrete GS alpha-mediated responses that accompany homologous or heterologous desensitization in two related somatic hybrids

1. Prostacyclin and adenosine A2 receptors activate adenylate cyclase in the neuroblastoma hybrid cell lines NG108-15 and NCB-20. Prolonged exposure of NG108-15 cells to iloprost (a stable analogue of prostacyclin) results in a subsequent reduction in the capacity for adenylate cyclase activation by iloprost, the adenosine analogue 5'-(N-ethyl)-carboxamidoadenosine (NECA) or NaF. In contrast prolonged exposure of NCB-20 cells to iloprost results only in the loss of iloprost responsiveness. 2. Iloprost pretreatment of NG108-15 cells also magnified the morphine-dependent inhibition of iloprost-stimulated adenylate cyclase activity from 36 to 48%. This change was not due to lower iloprost stimulation following desensitization, since the % inhibition of adenylate cyclase activity by morphine in control cells was constant irrespective of enzyme activity. 3. These heterologous effects observed in NG108-15 cells following iloprost pretreatment may involve changes in the GS alpha protein, since there was a reduction of about 30% in the cholera toxin-induced [32P]-ADP-ribosylation of a 45 kDa protein from cell membranes (corresponding to the extent of loss of NECA or NaF responsiveness). A similar reduction was not observed in NCB-20 cells. 4. These results indicate that iloprost pretreatment induces different forms of desensitization in NG108-15 and NCB-20 cell lines. The heterologous desensitization in the former may, like the human platelet, involve a functional loss of GS alpha from the cell membrane. Changes in the activity of GS alpha may also account for the heterologous effects on receptors that mediate inhibition of adenylate cyclase.

Five-year outcome of infants of birthweight 500 to 1500 grams: relationship with neonatal ultrasound data

Of 154 consecutive survivors of birthweight 500 to 1500 gm, 139 (90.3%) were seen at 5 years of age, corrected for prematurity, and 137 (89%) were able to be fully assessed by both the psychologist and pediatrician. All but two children had had serial cranial ultrasonography with a linear array real-time scanner in the neonatal period. At 5 years, of 39 children with cerebral ultrasound abnormalities detected during their primary hospitalization, seven (17.9%) had cerebral palsy, but 32 (82.1%) did not. A further three children with cerebral palsy at 5 years had had no cerebral abnormalities on ultrasound. Of the cerebral abnormalities diagnosed by ultrasound, ventricular dilation, with or without cerebroventricular hemorrhage, had the highest positive predictive value (40%) for cerebral palsy at 5 years. In the 127 children free from cerebral palsy at 5 years, two (1.6%) had severe intellectual impairment, both of whom had had normal cerebral ultrasonography. Although neonatal cranial ultrasonography with a linear array was somewhat predictive of cerebral palsy at 5 years, the majority of infants with abnormal scans had no severe sensorineural impairments at 5 years.

A selective binding site for 3H-NECA that is not an adenosine A2 receptor

In homogenates of NG108-15 cells, adenosine analogues activate adenylate cyclase with the following order of potency: N-ethylcarboxamidoadenosine (NECA) greater than 2-chloroadenosine greater than N6-(L-phenylisopropyl)-adenosine (PIA) = cyclohexyladenosine = 2-phenylaminoadenosine. Adenosine receptor antagonists inhibit NECA-stimulated adenylate cyclase activity with the order of potency 3-isobutyl-1-methyl-xanthine (IBMX) greater than theophylline greater than caffeine. These data suggest that these ligands act at an adenosine A2 receptor. There is an apparently homogenous population of saturable 3H-NECA binding sites in homogenates of NG108-15 cells. These sites have an affinity for 3H-NECA of approximately 1 microM, and are present at a density of approximately 10 pmol/mg protein. Unlabelled NECA, 2-chloroadenosine, IBMX and theophylline displace 3H-NECA binding, with an order of potency that suggests that the 3H-NECA binding site may represent an adenosine A2 receptor. However, PIA, cyclohexyladenosine and 2-phenylaminoadenosine produce no detectable displacement of 3H-NECA binding at concentrations that produce a maximal stimulation of adenylate cyclase activity. Pretreatment of NG108-15 cells with either NECA or PIA produces a homologous desensitization of subsequent responses to all the adenosine analogues, with no effect on subsequent responses to a prostacyclin receptor agonist or NaF. This suggests that all the adenosine analogues examined activate an adenosine A2 receptor. Therefore, the 3H-NECA site at which PIA is inactive cannot represent this receptor.

Selective improvement in cognitive test scores of extremely low birthweight infants aged between 2 and 5 years

The cognitive development at 2 and 5 years of a cohort of extremely low birthweight (ELBW) children (birthweight 500-999 g) was compared with that of cohorts of larger very low birthweight (VLBW) children (birthweight 1000-1500 g) and normal birthweight (NBW) children (birthweight greater than 2500 g) to determine whether the improvements in cognitive function of ELBW infants between 2 and 5 years are apparent or real. At 2 years of age, ELBW children had a mean Mental Developmental Index (MDI) on the Bayley Scales of 90.4, significantly lower than the means of 100.3 for the larger VLBW children (P = 0.006), and 107.8 for the NBW children (P = 0.0002). However by 5 years the mean scores on the Wechsler Preschool and Primary Scales of Intelligence (WPPSI) full-scale for the ELBW and larger VLBW children were virtually identical (105.9 and 106.0 respectively)--but still lower than the mean WPPSI full-scale of 114.6 for the NBW children. After standardizing the MDI and WPPSI scores relative to the NBW children, the ELBW children improved between 2 and 5 years (paired t-test, t = 3.2, P = 0.004) whereas the larger VLBW infants did not. We postulate that ELBW children require more time than larger VLBW children after birth to compensate for perinatal and other stresses, and that developmental delay at 2 years may not always persist to 5 years.

Increased caudate dopamine turnover may contribute to the recovery of motor function in marmosets treated with the dopaminergic neurotoxin MPTP

Administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to common marmosets initially impaired motor function, but a partial recovery occurred over the following weeks. At both 10 days and 4-6 weeks following MPTP treatment, [3H]dopamine ([3H]DA) uptake into synaptosomal preparations of putamen was markedly decreased. At 10 days and 4-6 weeks following MPTP treatment DA, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in the caudate nucleus and nucleus accumbens were substantially reduced. However, the levels of HVA and DOPAC in caudate nucleus were higher at 4-6 weeks than at 10 days. The ratio of (DOPAC + HVA)/DA in caudate nucleus was elevated at 10 days following MPTP treatment and even more so at 4-6 weeks. No change in Bmax or Kd values for [3H]spiperone binding to caudate preparations were observed. The recovery of motor function in marmosets observed following MPTP treatment may result partially from a compensatory increase in caudate DA turnover by remaining neurones.

Beta-adrenergic relaxation of dog trachealis: contractile agonist-specific interaction

The phenomenon of contractile agonist-dependent relaxation by isoproterenol (ISO) of active tension elicited by acetylcholine (ACh), histamine (HIS), serotonin (5-HT), and potassium chloride-substituted Krebs-Henseleit solution (KCl) was studied in 210 tracheal smooth muscle (TSM) strips from 28 mongrel dogs in vitro. All TSM strips were contracted to similar active tensions [target tension (TT) = 50% of the maximal active tension elicited by 127 mM KCl] with ACh, HIS, 5-HT, or KCl and relaxed with either ISO, forskolin (FSK), N6,2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (db-cAMP), or 3-isobutyl-1-methylxanthine (IMX). The concentrations of ISO causing 50% relaxation from TT (RC50) were ACh (2.9 +/- 1.1 x 10(-6) M) greater than 5-HT (8.4 +/- 1.5 x 10(-8) M) approximately KCl (8.1 +/- 2.1 x 10(-8) M) greater than HIS (1.6 +/- 0.2 x 10(-8) M). FSK and IMX relaxed TSM in the same rank order of potency as ISO. In contrast to the contractile agonist-dependent relaxation elicited by ISO, FSK, and IMX, db-cAMP was nearly equipotent in relaxing similarly contracted strips. These results are consistent with contractile agonist-specific interaction with cAMP production by ISO and FSK. These data demonstrate that the phenomenon of contractile agonist-dependent relaxation by ISO is not related specifically to the beta-adrenoceptor.

Evidence for platelet-activating factor secretion during immune activation in dogs

To elucidate the potential physiological significance of platelet-activating factor (PAF) in acute bronchoconstriction, we studied the effect of Ascaris suum antigen on the tachyphylactic response to PAF in 15 natively allergic mongrel dogs in vivo. Active bronchial tension was measured isometrically, and mediator secretion was measured as the arteriovenous difference (AVd) in plasma concentration across the lungs. Administration of PAF into the bronchial artery caused dose-related contraction in five control dogs (maximal active tension = 11.8 +/- 1.68 g/cm) that paralleled the increase in the AVd for serotonin (4,188 +/- 175 pg/ml) but not histamine (maximal AVd less than 6.0 ng/ml). The response to PAF was highly tachyphylactic. In contrast to PAF, 1:10 concentration of intra-arterial antigen caused substantial release of histamine (AVd = 308 +/- 57.1 ng/ml; P less than 0.001 vs. PAF). Diminished responsiveness (2-log shift in threshold and maximal contraction; P less than 0.001) to PAF was demonstrated in five dogs after 1:10 antigen, compatible with endogenous release of PAF during prior immune challenge in the same animals. Administration of Ascaris antigen caused a leftward shift in the dose-response curve to serotonin and only mild tachyphylaxis to the maximal response to histamine. Our data are compatible with physiological participation of PAF in eliciting bronchial smooth muscle contraction during the acute phase of immune activation caused by A. suum antigen.

Expression and desensitisation of A2 purinoceptors on cultured bovine aortic endothelial cells

Purine nucleotides and their metabolites are important mediators of vascular tone. Adenosine promotes relaxation of vascular smooth muscle, acting on the A2 subclass of purinoceptors. There is some evidence that these receptors are also present on vascular endothelial cells. We have therefore examined cultured aortic endothelial cells for adenosine (A2) sensitivity. Bovine aortic endothelial cells (AG4762) were obtained from the Institute of Aging cell repository (USA), and cultured in monolayer flasks. Adenylate cyclase activity in homogenates of AG4762 cells was increased by 5'-(N-ethylcarboxamido)-adenosine (NECA) greater than 2-chloroadenosine greater than adenosine. NECA dependent activation of adenylate cyclase was inhibited by 3-isobutyl-l-methylxanthine greater than theophylline greater than caffeine. The rank order of potency of these compounds identified the responses as mediated by A2 purinoceptors. Prolonged exposure of AG4762 cells to NECA in culture resulted in loss of A2 purinoceptor responsiveness, and purinoceptor activity could be restored to non-dividing densensitized cells by further culture in the absence of the desensitising agent. The cyclic AMP dependent phosphorylation of specific sites in endothelial cells may trigger a number of important biological events which are yet to be determined.

Hypertension: variations in prevalence in the black population

Prevalence trends in hypertension in black men and women show an inversion at about ages 45 to 54 years. Incidence, mortality, and treatment of hypertension after age 35 can probably be related to this inversion. Incidence data are inconsistent and scanty. Morbidity data are incomplete and mostly unreliable. Mortality data partially explain the inversion. Long-term epidemiologic studies of hypertension in black elderly persons are needed to explain these variations in prevalence, which may have a beneficial impact on treatment and prognosis.

Ca2+-dependent facilitated shortening in isotonic contraction of trachealis muscle

We compared isotonic shortening with isometric force generation as a function of external Ca2+ in 166 tracheal smooth muscle (TSM) strips from 27 mongrel dogs in vitro. Concentration-response curves were generated with muscarinic stimulation (acetylcholine, ACh), alpha-adrenergic receptor activation (norepinephrine after beta-adrenoceptor blockade, NE), serotonin (5-HT), and KCl-substituted Krebs-Henseleit solution. The concentrations of 5-HT causing half-maximal shortening (ECS50, 1.54 +/- 0.14 X 10(-7) M) and half-maximal active isometric tension (ECT50, 1.72 +/- 0.30 X 10(-7) M) were similar (P = NS). Likewise, ECS50 (21.9 +/- 0.7 mM) and ECT50, (22.0 +/- 0.9 mM) were similar for KCl. In contrast, facilitated isotonic shortening (i.e., greater isotonic shortening for comparable degrees of force generation) was elicited with ACh and NE for all levels of force generation between 15 and 85% of maximum and for all concentrations of ACh from 3 X 10(-8) to 3 X 10(-5) M (P less than 0.05 for all points). Facilitated isotonic shortening also was elicited for all concentrations of NE from 10(-8) to 10(-6) M (P less than 0.05 for all points). Removal of Ca2+ from the perfusate substantially reduced the potency of ACh (P less than 0.001) and abolished differences between ECS50 (2.23 +/- 0.28 X 10(-5) M) and ECT50 (2.50 +/- 0.46 X 10(-5) M, P = NS). We demonstrate that for comparable degrees of force generation, muscarinic and alpha-adrenergic receptor activation cause greater isotonic shortening than KCl or 5-HT and that this facilitated shortening is associated with the concentration of external Ca2+.

The use of calcium channel blockade for the prevention of postoperative adhesion formation

Prevention of postoperative adhesion formation is an issue of fundamental concern to the reproductive surgeon. The disappointing results of current adjunctive regimens have prompted a search for more potent antiadhesion therapies. Administration of nifedipine hydrochloride, a prototypical calcium channel blocking agent, to hamsters receiving a standardized traumatic lesion of the left uterine horn significantly inhibited primary adhesion formation as compared to control animals. These preliminary results suggest that calcium channel blockade may have the potential to favorably influence events related to peritoneal repair; further study of these agents as surgical adjuvants in the treatment of chronic pelvic adhesive disease is indicated.

Dopamine receptor stimulation does not affect phosphoinositide hydrolysis in slices of rat striatum

The effect of dopamine receptor stimulation on the accumulation of labelled inositol phosphates in rat striatal slices under basal and stimulated conditions was examined following preincubation with [3H]inositol. Incubation of striatal slices with the selective D-1 agonist SKF 38393 or the selective D-2 agonist LY 171555 for 5 or 30 min did not affect the basal accumulation of labelled inositol mono-, bis-, tris-, and tetrakisphosphate. Resolution by HPLC of inositol trisphosphate into inositol-1,3,4-tris-phosphate and inositol-1,4,5-trisphosphate isomers revealed that under basal conditions dopamine did not influence the accumulation of inositol-1,4,5-trisphosphate. Depolarisation evoked by KCl, or addition of the muscarinic receptor agonist carbachol, produced a marked increase in the accumulation of labelled inositol phosphates in both the presence and absence of lithium. Addition of dopamine did not reduce the ability of KCl or carbachol to increase inositol phospholipid hydrolysis. In the presence of lithium, dopamine (100 microM) enhanced KCl-stimulated inositol phospholipid hydrolysis, but this effect appears to be mediated by alpha 1 adrenoceptors because it was blocked by prazosin. SKF 38393 (10 microM) or LY 171555 (10 microM) also did not affect carbachol-stimulated inositol phospholipid hydrolysis. These data, in contrast to recent reports, suggest that striatal dopamine receptors do not appear to be linked to inositol phospholipid hydrolysis.

Identification of the C5a des Arg cochemotaxin. Homology with vitamin D-binding protein (group-specific component globulin)

The chemotactic activity of human C5a des Arg is enhanced significantly by an anionic polypeptide (cochemotaxin) in normal human serum and plasma. The cochemotaxin attaches to sialic acid residues within the oligosaccharide chain of native C5a des Arg to form a complex with potent chemotactic activity for human PMN. We investigated the nature of the cochemotaxin and found that vitamin D-binding protein is the putative cochemotaxin. Vitamin D-binding protein enhanced the chemotactic activity of native C5a des Arg, but had no effect on the chemotactic activity of either native C5a or FMLP. Sialic acid prevented both enhancement by vitamin D-binding protein of the chemotactic activity of native C5a des Arg and formation of C5a des Arg-vitamin D-binding protein complexes, detected by molecular sieve chromatography. Furthermore, vitamin D-binding protein and cochemotaxin exhibited identical molecular weights, isoelectric points, antigenic reactivity, and amino acid composition.