Functional heterogeneity of human term cytotrophoblasts revealed by differential sensitivity to extracellular Ca2+ and nucleotides

We have prepared purified cytotrophoblasts from human term placentas and examined the sensitivity of fura-2 loaded cells to the nucleotides ATP and UTP and to changes in extracellular Ca2+ concentration ([Ca2+]o). Purified cytotrophoblasts were obtained by collagenase digestion and separation according to density using self-generated Percoll gradients. The cytotrophoblast fraction was free of red cell and largely free of white cell contamination (as assessed by uniformly negative staining for vimentin and the failure of > 90% of fura-2 loaded cells to respond to the chemotactic peptide fMet-Leu-Phe). Purified cells secreted progesterone in a linear fashion over several hours in the presence of 25-hydroxycholesterol. The cells ranged in size from approximately 7.5 to 50 microns in diameter as described previously for purified cytotrophoblasts, and an analysis of cells for sensitivity to [Ca2+]o or nucleotides suggested functional heterogeneity within the cytotrophoblast population. Small cells (7.5-10 microns) were negative for cytokeratin-8 and, after loading with fura-2, were insensitive to extracellular nucleotides but sensitive to elevations in [Ca2+]o. Medium-sized cells (12-20 microns) were largely cytokeratin-positive (70% of cells) and sensitive to both ATP and UTP but largely insensitive to [Ca2+]o. Large cells (25-50 microns) were uniformly cytokeratin-positive (100% of cells) and, after fura-2 loading, sensitive to both [Ca2+]o and extracellular ATP or UTP. We examined the likely origin of small, medium and large cytotrophoblasts using an immunomagnetic cell sorting procedure that separates villous cytotrophoblasts (which do not express major histocompatibility class I antigens) from extravillous cytotrophoblasts. This procedure resulted in the selective sedimentation of almost all medium and large cells, leading to the conclusion that the small cells were villous cytotrophoblasts whereas medium and large cells were predominantly extravillous in origin. The data suggest that small, medium and large cytotrophoblasts have distinct roles in the function of the term placenta.

Mapping of hereditary neuralgic amyotrophy (familial brachial plexus neuropathy) to distal chromosome 17q

Hereditary neuralgic amyotrophy with predilection for the brachial plexus (HNA) is an autosomal dominant disorder associated with recurrent, episodic, painful brachial neuropathies. Mildly dysmorphic facial features, including hypotelorism, long nasal bridge, and upslanting palpebral fissures, are present in affected persons in some pedigrees with HNA. To determine the chromosomal location of the HNA gene, we carried out genetic linkage studies with polymerase chain reaction-based DNA markers in two large pedigrees. Linkage to markers from the distal long arm of chromosome 17 was established.

Selective inversion investigations of slow molecular motion in solid state deuteron NMR spectroscopy

Deuteron selective inversion experiments are reported for polycrystalline dimethyl sulfone-d6 as a function of temperature from 288 to 333 K. Double side-band modulation was used to achieve efficient off-resonance orientation-selective inversion. Fitting the selective inversion-recovery curves to two-site jump equations yields the motional rate. Temperature dependent jump rates, obtained from both selective inversion and deuteron quadrupole echo lineshapes, give an activation energy Ea = 86.5 +/- 1.4 kJ mol-1 and a frequency factor In(A) = 39.2 +/- 0.5. These values differ significantly from those of earlier 13C lineshape studies. At 298 K, variable power excitation was used to determine the underlying orientation dependent homogeneous linewidth, which is predominantly dipolar. The temperature dependence of the homogeneous linewidth is a sensitive indicator of large angle jump motion in the range 10(3)-10(4) s-1.

Iron deficiency in Massachusetts communities: Socioeconomic and demographic risk factors among children

OBJECTIVES

This study examined the association between community rates of iron deficiency in children and sociodemographic characteristics of Massachusetts communities.

METHODS

Between April 1990 and March 1991, 238 273 Mssachusetts children 6 through 59 months of age were screened; iron deficiency was defined as an erythrocyte protopophyrin concentration of 0.62 micromol/L or higher and a blood lead level of less than 1.2 micromol/L. Sociodemographic data were obtained from the 1990 US Census.

RESULTS

Five percent of communities had iron deficiency rates greater than 13.9 per 100 children screened. Iron deficiency rate was positively associated with proportion of Southeast Asians (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 1.08, 1.12), proportion of Hispanics (OR = 1.008, 95% CI = 1.002, 1.013), and high school incompletion (OR = 1.028, 95% CI = 1.020, 1.035). Similarly, an examination of three Massachusetts cities indicated that the iron deficiency rate was higher for children with Southeast Asian (relative risk [RR] = 3.6, 95% CI = 3.3, 3.8) and Hispanic (RR = 1.6, 95% CI = 1.5, 1.8) surnames than for all other children.

CONCLUSIONS

Wide variation exists in iron deficiency rates for children in Massachusetts communities. Community iron deficiency was associated with low socioeconomic status and high proportions of Southeast Asians and Hispanics.

Chronic inflammatory demyelinating polyneuropathy associated with malignant melanoma

We report three patients who developed chronic inflammatory demyelinating polyneuropathy (CIDP) in association with malignant melanoma. In two cases, melanoma was discovered during the initial evaluation for neuropathy. Two patients also had vitiligo, an antibody-mediated disorder that may complicate melanoma. Melanoma cells and Schwann cells are both of neuroectodermal cell origin, with shared surface antigens. Shared immunoreactivity may account for the association between melanoma and CIDP, as with vitiligo.

Graded fibronectin receptor aggregation in migrating cells

We have examined the distribution of the integrin fibronectin receptor in migrating NIH 3T3 fibroblasts to test the hypothesis that cell locomotion involves regional differences of adhesive receptor aggregation. A distinct asymmetry of fibronectin receptor aggregation was observed on the surface of migrating NIH 3T3 fibroblasts. Direct current electric fields were used to stimulate directional cell migration and thus allow the quantitative correlation of receptor asymmetries to the direction of cell locomotion. Digital particle analysis of fluorescent confocal micrographs demonstrates that the leading half of cells has a higher proportion of receptors contained in small clusters than does the trailing half. Conversely, larger receptor aggregates are more prevalent in the rear of the cell than in the front. We have also observed a gradient of extracellular fibronectin fibril assembly, similar to that described for the fibronectin receptor. Extracellular fibronectin appears in progressively larger fibrils across the ventral cell surface from front to rear, with dense meshworks often deposited as a trail behind the cell. Large fibronectin receptor clusters toward the rear of the cell generally do not correlate with focal contacts, and are thus most likely aggregated by cell surface-bound fibronectin fibrils and not by adhesion to the substratum. These results suggest that spatial variations in the degree of adhesive receptor aggregation are created in fibroblasts during the processes of migration and matrix synthesis.

Relief of severe hyperacusis and diplacusis in a deafened ear by cochlear labyrinthectomy

A professional musician with intolerable hyperacusis and dysharmonic diplacusis in a severely deafened ear was successfully relieved of his symptoms by deliberate destruction of the cochlea.

Calcitonin gene-related peptide as an endogenous vasodilator: immunoblockade studies in vivo with an anti-calcitonin gene-related peptide monoclonal antibody and its Fab' fragment

1. Calcitonin gene-related peptide (CGRP) is localized in perivascular sensory neurons and is a potent vasodilator. We investigated the utility of immunoblockade as an in vivo technique for probing the role of CGRP as an endogenous vasodilator. 2. The effects of an anti-CGRP monoclonal antibody (MAb; coded C4.19) and its Fab' fragment on CGRP-induced changes in blood pressure and skin blood flow were studied in pentobarbitone-anaesthetized rats. Antidromic skin vasodilatation in the rat hind paw was measured by laser Doppler fluxmetry. 3. The dose-response relationship for the hypotensive effect of intravenous rat alpha CGRP (r alpha CGRP) was similarly shifted rightward by MAb C4.19 IgG (1 mg/rat; intravenously) and Fab' fragment (2 mg/rat; intravenously). The C-terminal fragment of human alpha CGRP (h alpha CGRP8-37) also blocked the hypotensive effect of r alpha CGRP. 4. MAb C4.19 Fab' fragment (2 mg/rat; intravenously) and h alpha CGRP8-37 (100 nmol/kg; intravenously), but not MAb C4.19 IgG (up to 3 mg/rat; intravenously) or normal mouse Fab' fragment (2 mg/rat; intravenously), blocked the increased skin blood flow response to antidromic stimulation of the saphenous nerve. 5. The mean percentage changes in skin blood flow parameters due to MAb C4.19 Fab' fragment were significantly different from those due to normal mouse Fab' fragment (unpaired t-test; P < 0.05) but not from those due to h alpha CGRP8-37. 6. The results demonstrate the pharmacokinetic advantage of Fab' fragment over IgG for immunoblockade studies in vivo and support the role of CGRP in mediating skin vasodilatation.

Messenger RNAs encoding the natriuretic peptides and their receptors are expressed in the eye

The rates of secretion and removal of aqueous humour are major determinants of intraocular pressure (IOP). The natriuretic peptides, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) are vasodilators with variable effects on electrolyte and water transport at sites such as the nephron. There is some evidence that they may also affect fluid balance in the eye. As a first step in understanding the function of these peptides in the eye, we have used the technique of cDNA amplification with the polymerase chain reaction to demonstrate the presence of mRNA transcripts encoding the three natriuretic peptide receptors (NPR-A, NPR-B and NPR-C) in the retina, choroid and ciliary process of the rat and rabbit eye. In addition we have observed a differential distribution of ANP, BNP and CNP mRNAs in ocular tissues suggesting that at least part of the natriuretic peptide immunoreactivity detected in the eye arises from local synthesis of peptide. Thus, the eye appears to be able to synthesize all the components of the natriuretic peptide system necessary to modulate IOP independently of changes in the plasma concentrations of these peptides.

Renin-angiotensin system gene polymorphisms influence blood pressure and the response to angiotensin converting enzyme inhibition

OBJECTIVES

To investigate the relationship between polymorphisms in the angiotensin converting enzyme (ACE), angiotensinogen (AGT) and type 1 angiotensin-II (AT1R) genes and (1) quantitative variations in blood pressure and (2) the blood pressure response to ACE inhibition in a hypertensive cohort.

DESIGN AND METHODS

We administered monotherapy with ACE inhibitors to 125 previously untreated essential hypertensives. Genotypes for ACE insertion and deletion, AGT M235T and AT1R A1166-->C polymorphisms were determined in DNA extracted from peripheral blood leucocytes. The influence of genotype on pretreatment blood pressure and the ACE inhibitor-induced decrease in blood pressure was tested by analysis of variance and multiple regression analysis, adjusting for age, sex, body mass index, alcohol intake and, where appropriate, pretreatment blood pressure.

RESULTS

ACE and AT1R genotypes were independent predictors of pretreatment systolic and diastolic blood pressure, with an apparent interaction between these two gene loci. Although it did not influence pretreatment blood pressure in this population, AGT genotype was an independent predictor of the blood pressure response to ACE inhibition.

CONCLUSIONS

The ACE and AT1R gene loci (chromosomes 17q and 3q, respectively) may carry alleles influencing blood pressure variation in this hypertensive population, with a possible epistatic interaction between the two loci. The AGT T235 allele does not appear to be a marker for blood pressure variation in this group, but variants on chromosome 1q lying in or near the AGT gene may contribute to individual differences in the blood pressure response to ACE inhibition. Among essential hypertensives, differences in the ACE inhibitor response appear, in part, to be genetically determined.

Differences in transcription and translation of long and short Gs alpha, the stimulatory G-protein, in human atrium

1. We have previously reported the relative mRNA and protein level of the long and short splice variants of Gs alpha (Gs alpha L and Gs alpha S) in human atrium. We have now measured the relative proportions of the serine+ and serine- variants of Gs alpha L and Gs alpha S in human atrium, and assessed, indirectly, whether their differential expression may (i) regulate Gs alpha phosphorylation, and (ii) be regulated by atrial cyclic AMP levels. 2. The serine+ and serine- variants of Gs alpha L and Gs alpha S were estimated by single nucleotide primer extension in 36 right atrial strips of which half were from beta-adrenoceptor-blocked patients. The ratio of serine+ to serine- variants was 0.06 +/- 0.12 for Gs alpha L, compared with 8.04 +/- 12.16 for Gs alpha S (P < 0.001). 3. Isoelectric points of Gs alpha and Gs alpha S in the atria of four beta-adrenoceptor-blocked and four non-beta-adrenoceptor-blocked patients were estimated by two-dimensional gel electrophoresis. Two-dimensional gel analysis gave a consistent pattern with several spots for both Gs alpha L and Gs alpha S; however, the isoelectric points of Gs alpha S were more acid (5.18 +/- 0.24) than those of Gs alpha L (5.87 +/- 0.17, P < 0.001). 4. No significant difference in either the serine variants or isoelectric point value was observed between beta-adrenoceptor-blocked and non-beta-adrenoceptor-blocked patients. 5. In conclusion, all four Gs alpha variants were expressed in human atrium, but Gs alpha L is almost entirely of the serine- form. Gs alpha S has a more acidic isoelectric point than Gs alpha L, indicating a possible post-translational modification. The lack of difference in our results between beta-adrenoceptor-blocked and non-beta-adrenoceptor-blocked patients suggests indirectly that cyclic AMP is an unlikely candidate for regulating splicing or post-translational modification of Gs alpha in vivo.

Management of hypertension in general practice: agreements with and variations from the British Hypertension Society guidelines

A random sample of 200 East Anglian general practitioners was surveyed to establish current trends in the management of hypertension, including measurement of blood pressure (BP), patient investigation, treatment and follow-up. A total of 125 (62.5%) completed questionnaires was returned. Responses were used to assess the range of self-reported management practice and the extent of conformity with the British Hypertension Society guidelines. Although there was a broad spectrum of reported practice, many respondents adhered closely to the guidelines in relation to BP measurement, use of non-pharmacological treatment, treatment goals, choice of drug and patient investigation. Not surprisingly, the greatest disparity between reported and recommended practice occurred in areas where guidelines have only recently become available: treatment of isolated systolic hypertension and of the elderly hypertensive. Here, the survey provides a useful baseline against which to monitor future changes in management.

Polyketide synthesis in vitro on a modular polyketide synthase

BACKGROUND

The 6-deoxyerythronolide B synthase (DEBS) of Saccharopolyspora erythraea, which synthesizes the aglycone core of the antibiotic erythromycin A, contains some 30 active sites distributed between three multienzyme polypeptides (designated DEBS1-3). This complexity has hitherto frustrated mechanistic analysis of such enzymes. We previously produced a mutant strain of S. erythraea in which the chain-terminating cyclase domain (TE) is fused to the carboxyl-terminus of DEBS1, the multienzyme that catalyzes the first two rounds of polyketide chain extension in S. erythraea. This mutant strain produces triketide lactone in vivo. We set out to purify the chimaeric enzyme and to determine its activity in vitro.

RESULTS

The purified DEBS1-TE multienzyme catalyzes synthesis of triketide lactones in vitro. The synthase specifically uses the (2S)-isomer of methylmalonyl-CoA, as previously proposed, but has a more relaxed specificity for the starter unit than in vivo.

CONCLUSIONS

We have obtained a purified polyketide synthase system, derived from DEBS, which retains catalytic activity. This approach opens the way for mechanistic and structural analyses of active multienzymes derived from any modular polyketide synthase.

A comparison of the contractile effects of 5-hydroxytryptamine, sumatriptan and MK-462 on human coronary artery in vitro

1. MK-462 (N,N-dimethyl-2-[5-(1,2,4-triazol-1-ylmethyl)-1H- indol-3-yl]ethylamine) is a novel selective 5-HT1D-receptor agonist which in clinical trials has been shown to be an effective antimigraine agent. As angiographic studies have shown that sumatriptan (an established 5-HT1D-receptor agonist) can cause coronary artery vasoconstriction in patients, we compared the effects of MK-462 with those of 5-HT and those of sumatriptan, on isolated segments of human coronary artery in vitro. 2. Coronary arteries were obtained from explanted hearts from patients (n = 22, 2 females, 20 males, aged 21-60 years) undergoing cardiac transplantation. Endothelium-denuded ring segments of coronary artery, 2mm long were mounted in organbaths for isometric tension recording. For each arterial ring segment, a cumulative concentration-effect curve to either 5-HT, sumatriptan or MK-462 was determined. After maximal response to each agonist had been obtained, ketanserin (a 5-HT2 receptor antagonist) 0.6 microM was added to the tissue bath, followed by methiotepin (0.6 microM) and the reduction in tension produced by the addition of each antagonist was determined. 3. Out of 22 coronary arteries studied, only 10 showed any response (contraction) to 5-HT. Not all arteries which responded to 5-HT contracted in response to both sumatriptan and MK-462 (one ring from each artery being exposed to a single agonist in each case).(ABSTRACT TRUNCATED AT 250 WORDS)

Hutchinson's sign and its importance in rhinology

Herpes zoster ophthalmicus usually has a typical appearance. However, if the disease is limited to the nasociliary branch of the trigeminal nerve, the ocular appearance may be confusing. Hutchinson in 1865 first noted that involvement of the external nasal branch of the fifth cranial nerve was associated with an increased incidence of ocular zoster. A case of herpes zoster ophthalmicus is presented that clinically resembled an ocular complication of sinus disease. The presence of a localized vesicular rash at the nasal tip assisted in an early diagnosis. Although this sign is known amongst ophthalmologists, its importance in rhinology is stressed. An anatomical explanation of Hutchinson's sign is given and the treatment of herpes zoster ophthalmicus is briefly discussed.

A simple molecular assay for the C1166 variant of the angiotensin II type 1 receptor gene

Studies of human polygenic diseases require the genotyping of polymorphic markers from large numbers of subjects. The rapid detection of the insertion (I)/deletion(D) polymorphism of the angiotensin converting enzyme (ACE) gene by the polymerase chain reaction (PCR) has facilitated the study of this locus in a a number of cardiovascular diseases, but not all gene polymorphisms are as easily detected. We describe a rapid mismatch-PCR/restriction fragment length polymorphism (RFLP) assay for the C1166 variant of the angiotensin II type 1 receptor gene, a mutation which may interact with the ACE polymorphism in the determining of risk of myocardial infarction. This rapid assay, which requires no special equipment or expertise, will be useful in confirming the interaction between these two gene loci. The principles utilised can be applied more generally to the detection of any polymorphic single base substitution.

Repositioning of a domain in a modular polyketide synthase to promote specific chain cleavage

Macrocyclic polyketides exhibit an impressive range of medically useful activities, and there is great interest in manipulating the genes that govern their synthesis. The 6-deoxyerythronolide B synthase (DEBS) of Saccharopolyspora erythraea, which synthesizes the aglycone core of the antibiotic erythromycin A, has been modified by repositioning of a chain-terminating cyclase domain to the carboxyl-terminus of DEBS1, the multienzyme that catalyzes the first two rounds of polyketide chain extension. The resulting mutant markedly accelerates formation of the predicted triketide lactone, compared to a control in which the repositioned domain is inactive. Repositioning of the cyclase should be generally useful for redirecting polyketide synthesis to obtain polyketides of specified chain lengths.

Alpha-blockade and calcium antagonism: an effective and well-tolerated combination for the treatment of resistant hypertension

OBJECTIVE

To test whether the combination of calcium antagonism is additive with the other newer antihypertensives, namely alpha-blockers and angiotensin converting enzyme (ACE) inhibitors.

DESIGN

Three-way double-blind, Latin-square crossover studies in two groups of 12 patients with essential hypertension. The three treatment periods were amlodipine, doxazosin (study A) or enalapril (study B), and the combination of amlodipine with the second drug.

METHODS

Each treatment was taken for 1 month, preceded by a 2-week single-blind run-in period, in which the patients received a low dose of doxazosin (study A) or enalapril (study B) to enable recruitment of patients with moderate or severe hypertension. Blood pressure, foot volume and plasma noradrenaline concentration were measured at the end of each run-in and treatment period.

RESULTS

The combination of alpha-blockade and calcium antagonism caused a fall in supine and erect blood pressures. These falls were significantly greater than on either drug alone, and greater than the sum of the falls when taking the individual drugs. The combination of amlodipine and the ACE inhibitor was also additive. Both combinations with amlodipine were tolerated well by all patients.

CONCLUSIONS

The combination of alpha-blockade and calcium antagonism has not previously been studied and should be useful for resistant hypertensives who have not tolerated beta-blockade or ACE inhibitors. The combination of ACE inhibition and calcium antagonism has previously been shown to be additive; its use as a positive control in the present studies suggests that the use of an active drug for a run-in period may be a useful design for permitting the study of patients from whom all treatment cannot safely be withdrawn.