The relationship between innervation and arterial structure in late prenatal and early postnatal development of the rat jejunal artery

The peripheral nervous system exerts a trophic influence on target tissues. We have examined the development of the perivascular innervation of the rat jejunal artery and correlated the simultaneous development of the endothelium and medial smooth muscle. Before birth a close relationship exists between endothelial cells and the first layer of differentiating medial smooth muscle, whereas the nerve fibres at this stage are formed into large remote bundles. After birth the differentiation of the media continues and the endothelial cells become separated from the smooth muscle by a thick internal elastic lamina. The nerve fibres grow from the large peripheral bundles to reach the smooth muscle as small bundles or individual fibres, with those immunoreactive to anti-calcitonin gene-related peptide being best developed by birth. From these studies it would seem that it is unlikely that perivascular nerve fibres influence the early development of the arterial wall, but they suggest that endothelial cells are more likely to be involved.

Antenatal diagnosis of cephalothoracopagus twins in a triplet pregnancy. A case report

The occurrence of conjoined twins in a triplet pregnancy is rare. Cephalothoracopagus twins were diagnosed on ultrasonography at 17 weeks' gestation. This is the first case of conjoined twins in a triplet pregnancy diagnosed early enough antenatally to allow vaginal pregnancy termination.

The peptidergic innervation of the developing mesenteric vascular bed in the rat

We have followed the development of perivascular nerve fibres using antisera to substance P, calcitonin gene related peptide, neuropeptide Y and vasoactive intestinal polypeptide in the mesenteric vascular bed of developing Sprague-Dawley rats. The pattern and density of innervation appeared to be determined by one week of age. The pattern of innervation by SP- and CGRP-positive fibres was similar. The pattern of innervation by neuropeptide Y-containing fibres was distinct from that of SP and CGRP. The VIP-positive fibre plexus was sparse and irregular compared with the others examined. The density of innervation by all fibre types was highest in the jejunal arteries.

The differential contribution by individual enzymes of glycolysis and protein catabolism to the relationship between heterozygosity and growth rate in the coot clam, Mulinia lateralis

The locus-specific effects of heterozygosity upon individual growth rate were determined for 15 polymorphic enzymes among 1906 individuals from a single cohort sample of the marine bivalve Mulinia lateralis. Two measures of individual growth rate (total wet weight and shell length) were made at collection and after a period of growth in the laboratory. The correlation between heterozygosity and growth rate was independently determined for each locus using multiple linear regression, thereby providing a rank of individual locus effects; these differed significantly. The four estimated rankings of relative locus effects (initial length, initial weight, length added in the laboratory, and added weight) were not statistically different. That is, a locus with a large effect of heterozygosity on growth rate in nature had a similarly large effect on laboratory growth rate. The effect of a locus was not related to heterozygosity per se; some highly heterozygous loci had no detectable correlation with growth rate. The data contained two pairs of relatively tightly linked loci; in both cases one locus of a pair had significant effects on growth rate, while the other had no effect. Loci with large and significant correlations with growth rate synthesize enzymes which function in protein catabolism or glycolysis; heterozygosity in enzymes of the pentose shunt, redox balance, or other miscellaneous metabolic roles was not correlated with growth rate. Since the metabolic basis for the correlation is known to derive from individual differences in net energy status, particularly energetic costs of whole-body protein turnover, these data indicate that phenotypic effects (e.g., variation in growth rate) are determined by heterozygosity at the studied genes, not other linked loci.

Apolipoprotein B allotypes MB19(1) and MB19(2) in subjects with coronary artery disease and hypercholesterolemia

We recently characterized a common form of genetic polymorphism in human apolipoprotein (apo) B, using the specific monoclonal antibody MB19 (Young SG, et al. Proc Natl Acad Sci USA 1986; 83:1101-1105). Antibody MB19 binds apo B with one of three distinct patterns of immunoreactivity (strong, intermediate, or weak). These three binding patterns are the result of the codominant inheritance of two common apo B alleles which encode for apo B allotypes MB19(1) and MB19(2), which have high and low affinity, respectively, for antibody MB19. Thus, subjects with strong or weak binding patterns are homozygous for MB19(1) or MB19(2), respectively, whereas those with an intermediate pattern are heterozygotes. To assess whether the MB19 polymorphism was related to hypercholesterolemia (HC) or to coronary artery disease (CAD), we determined the MB19 binding pattern and plasma lipoprotein concentrations in 129 normal subjects, 51 patients with HC, and 149 patients with CAD. The percentages of normal subjects having the strong, intermediate, and weak binding patterns were 11.6%, 41.9%, and 46.5%, respectively. The frequency of the three MB19 binding patterns was nearly the same in the groups with HC and CAD. Also, within each of the three groups of subjects, the MB19 binding pattern did not influence the plasma lipoprotein concentrations. We conclude that the genetic polymorphism in apo B defined by antibody MB19 is a common allelic variation in apo B, and that in the populations studied, it does not appear to be associated with the development of coronary artery disease or hypercholesterolemia.

Parallel expression of the MB19 genetic polymorphism in apoprotein B-100 and apoprotein B-48. Evidence that both apoproteins are products of the same gene

Immunochemical studies have demonstrated that apoprotein B-100 and apoprotein B-48 share some antigenic determinants, but whether they are products of the same gene has remained uncertain. Utilizing a specific mouse monoclonal antibody, MB19, we recently characterized a common form of genetic polymorphism that was expressed in apo-B-100 (Young, S. G., Bertics, S. J., Curtiss, L. K., Casal, D. C., and Witztum, J.L. (1985) Proc. Natl. Acad. Sci. U.S.A., in press). Antibody MB19 binds different allotypes of apo-B-100 (MB19(1) and MB19(2] with high and low affinities, respectively. Compared to a rabbit antiserum against human low density lipoprotein, which detects 100% of apo-B mass in all individuals, antibody MB19 detects 100% of apo-B with allotype MB19(1) but less than 10% of apo-B with allotype MB19(2). Western blots demonstrate that MB19 binds to both apo-B-100 and apo-B-48. To determine if apo-B-48 and apo-B-100 from the same individual express the same polymorphism, chylomicrons and very low density lipoproteins were isolated from 23 subjects in whom the allotypes of apo-B-100 were known. Delipidated apoproteins were separated electrophoretically and then transferred to nitrocellulose membranes. Nitrocellulose membranes were incubated with 125I-MB19 (to detect the polymorphism) and 131I-antiserum to human apo-B (to quantitate total apo-B transferred to nitrocellulose membranes). Apo-B-100 and apo-B-48 bands were removed and the ratio of 125/131 counts in each band was calculated. In all 23 subjects studied, the same MB19 polymorphism was present in both apo-B-100 and apo-B-48. This observation provides strong evidence that both apoproteins are products of the same gene.

Vascular and neural changes in the rat optic nerve following induction of diabetes with streptozotocin

This study was undertaken to determine whether or not changes occur in blood vessels, axons or glia of the optic nerve as the result of streptozotocin-induced diabetes. Diabetes was induced in 4 weeks old Sprague-Dawley rats. At 12 and 16 weeks of age, the rats were killed and the optic nerves prepared for examination. The number and density of blood vessels was found to be significantly increased in the diabetic rats. No alteration in the structure of the blood vessels was noted. A decrease in the percentage volume of axons and an increase in the percentage volume of glial elements accompanied the increase in blood vessels in the diabetic rats. No difference was found in the spectrum of fibre diameters.

An examination of the evidence for the existence of preformed pathways in the neural tube of Xenopus laevis

We have examined the neural tube in Xenopus laevis tadpoles to investigate the anatomical guidance elements which may be present in the presumptive marginal zone. With appropriate fixation protocols the neuroepithelial cells appeared in contact; electron microscopic observations failed to show any specialized intercellular spaces preceding the growing axons. The first fibres were found in the intercellular clefts between the neuroepithelial cells near the surface of the neural tube. Reconstructions of the neural tube from examination of serial 1 micron sections showed that the intercellular clefts are non-aligned at this stage and branching. Scanning electron microscopy of the surface of the neural tube confirmed that the intercellular spaces are non-aligned and often branch caudal to the growing front of descending axons. Thus to grow in a consistent direction the developing axons may have to make consistent and selective (specific) selections of pathway at numerous branch points if their growth is restricted to these intercellular clefts. As more axons grow along the neural tube, the intercellular clefts become wider, and the neuroepithelial cells bounding the clefts become indented. At later stages many fibres were observed with both scanning and transmission electron microscopy to grow along the surface of the neural tube. These changes in neuroepithelial cell morphology and fibre pathway allow axons to form bundles which take a fairly straight course in contrast to the winding path which must be taken by the first axons to grow through the intercellular clefts.

The relationship between altered blood vessel structure, hypertension, and the sympathetic nervous system

The relationship between sympathetic innervation and arterial medial development has been examined in normotensive, hypertensive, and diabetic rats. Using the jejunal artery as a model, the number of nerve fibres innervating the artery as determined from fluorescent preparations, and the medial thickness and lumen diameter as measured from resin embedded specimens were correlated from animals prepared in various ways. The rats used were normal Sprague-Dawley (SD), SD with induced hypertension, SD with diabetes induced with streptozotocin, SD sympathectomized with 6-hydroxydopamine, spontaneously hypertensive rats (SHR), SHR treated with capsaicin to prevent hypertension development, Wistar Kyoto rats (WKY), and WKY treated with capsaicin. Examination of the jejunal arteries from these rats at 12 weeks of age following normal development, or 8 weeks of hypertension development, or 8 and 12 weeks of diabetes, showed that increased innervation occurred in the SHR under all conditions, and in the diabetic rats after 8 weeks of diabetes. Medial hypertrophy occurred in the SHR and in the SD hypertensive only. It is concluded that the special relationship which exists between the sympathetic innervation and arterial media in the SHR does not occur during hypertension development in the SD rat, nor is it necessary for normal medial development in the SD rat. The sympathetic innervation does appear to have a trophic influence on vascular smooth muscle of diabetic rats, at least in the early stages of the disease.

Multiple-locus heterozygosity and the physiological energetics of growth in the coot clam, Mulinia lateralis, from a natural population

The relationship between individual energy budgets and multiple-locus heterozygosity at six polymorphic enzyme loci was examined in Mulinia lateralis. Energy budgets were determined by measuring growth rates, rates of oxygen consumption, ammonia excretion and clearance rates. Enzyme genotypes were determined using starch gel electrophoresis. Growth rate and net growth efficiency (the ratio of energy available for growth to total energy absorbed) increased with individual heterozygosity. The positive relationship between observed growth and multiple-locus heterozygosity was associated with a negative relationship between routine metabolic costs and increasing heterozygosity. Reduction in routine metabolic costs explained 60% of the observed increased growth of more heterozygous individuals. When routine metabolic costs were standardized for differences in feeding rates, these standard metabolic costs explained 97% of the differences in growth rate. Lower standard metabolic costs, associated with increasing heterozygosity, have been proposed as a physiological mechanism for the relationship between multiple-locus heterozygosity and growth rate that has been reported for a variety of organisms, ranging in diversity from aspens to humans. This study demonstrates that reduction of standard metabolic costs, at least in clams, accounts for virtually all of the differences in growth rate among individuals of differing heterozygosity.

The postnatal development of blood vessels in the optic nerve of normotensive and hypertensive rats

The blood vessels in the optic nerve of normotensive and hypertensive rats have been examined at 2, 4, 8 and 12 weeks of age. The pattern of development was found to be different in the two strains, with the number of blood vessels in the hypertensive rat optic nerve being lower at 2 weeks, but greater at 12 weeks than the normotensive rat. There appeared to be no correlation between vascularity and either myelination or changes in the fibre diameter spectrum at the ages studied. It is concluded that while the cause of the increased vascularity of the optic nerve in hypertensive rats is not known, it appears to be without effect in the structural development of the optic nerve.

The development of two subnuclei of the nucleus tractus solitarius in spontaneously hypertensive rats

Changes in relative metabolic requirements and neuronal densities in the nucleus commissuralis (NC) and nucleus medialis (NM) of the nucleus tractus solitarius were studied in spontaneously hypertensive rats (SHR) during development. The changes in relative metabolic requirements in the two subnuclei of SHR between 2 and 12 weeks of age were similar to those previously reported for normotensive WKY at the same ages. However, the relative metabolic activity in the NC of 2- and 4-week SHR was significantly higher than in normotensive rats. The differences in metabolic requirements of the NC could not be explained by differences in the neuronal densities of this subnucleus in young SHR and may reflect abnormalities in developmental or functional activities in the pre-hypertensive rat. Neuronal densities in the NC of 8- and 12-week SHR and in the NM of 4-, 8- and 12-week SHR were significantly higher than in WKY controls. Differences in the neuronal densities in the NC and NM of SHR may be explained by a smaller brain size characteristic of this strain, but differences in the NC of SHR suggest that the alterations may underlie or result from the cardiovascular abnormalities associated with the spontaneous hypertension of this strain.

The postnatal metabolic development of the nucleus commissuralis and nucleus medialis of the nucleus tractus solitarius

The ontogeny of the metabolic requirements in the nucleus commissuralis (NC) and nucleus medialis (NM) of the nucleus tractus solitarius was studied in the postnatal rat using the [3H]2-deoxy-D-glucose autoradiography technique. It was found that the metabolic requirements in the NC and NM are not constant between 2 and 12 weeks of age. A high level of metabolic activity at 2 and 8 weeks is contrasted by a lower level at 4 and 12 weeks. The apparent changes in metabolic requirements are not related to the changes in blood pressure of the rats or neuronal densities of the subnuclei which occur as the rats mature, or to exchange vessel densities of the subnuclei. Thus the higher energy requirements of the NC and NM at 2 and 8 weeks of age suggest that developmental and/or functional processes are more active at these stages.

The correlation between the development of sympathetic innervation and the development of medial hypertrophy in jejunal arteries in normotensive and spontaneously hypertensive rats

The catecholaminergic innervation of jejunal arteries was examined during development in normotensive and hypertensive rats. It was determined that a hyperinnervation of jejunal vessels in the hypertensive rats is present from 2 weeks of age onwards, before significant elevation of blood pressure and medial hypertrophy of jejunal arteries occurs. It is concluded that this hyperinnervation may be causally related to the medial hypertrophy in arteries of hypertensive animals.

Stool viruses in babies in Glasgow. 4. Further hospital studies

The events occurring during the time in hospital of 24 babies were recorded in detail, particularly those related to bowel function. The babies were admitted to a general paediatric unit with various diagnoses a total of 27 times during a six month period. The purpose of the study was to fill gaps in the records of a previous study (Scott et al. 1979) and to try to relate excretion of viruses detectable by electron microscopy to disturbances of bowel function (diarrhoea and/or vomiting). The results showed that a variety of viruses were associated with gastroenteropathy, that virus excretion could occur without disease and that hospital acquisition of virus is not uncommon. Antiobiotic treatment did not appear to precipitate diarrhoea in this small number of babies.

Factors involved in the control of RNA synthesis during regeneration of the optic nerve in the frog

The incorporation of tritiated uridine into retinal ganglion cells was studied following intra- and extracranial section of the optic nerve in the frog. It was found that incorporation increased to above control levels by two days following extracranial section of the optic nerve and by two weeks following intracranial section and was maintained at an elevated level until the regenerating optic nerve reached the diencephalon, at which point the rate of incorporation fell back to control levels. It is suggested that the signal for turning off increased uridine incorporation lies in the diencephalon, and that functional reconnection is not the signal.

Stereological analysis of the tunica media of the aorta and renal artery during the development of hypertension in the spontaneously hypertensive rat

The relationship between the arterial blood pressure and the composition of the tunica media in spontaneously hypertensive, Wistar-America and Wistar-Kyoto rats was examined. The systolic blood pressure of the spontaneously hypertensive rat, measured through an intra-arterial cannula, was significantly higher than that of the controls from 5 weeks and became hypertensive by 18 weeks of age. However, the content of the tunica media of the abdominal aortal and renal artery of the spontaneously hypertensive rats, as revealed by EM stereological analysis, and measurements of the thickness of the wall and diameter of the lumen, were not significantly different from the controls, at least up to the age of 18 weeks. The result of the present investigation suggests that the elevation of arterial blood pressure in the spontaneously hypertensive rat during the first 18 weeks of postnatal development is not a result of stereologically detectable changes in the composition of the tunica media of the abdominal aorta and renal artery.

A study of degeneration, scar formation and regeneration after section of the optic nerve in the frog, Rana pipiens

Degeneration, scar formation and regeneration have been studied after section of the optic nerve in the frog. In the normal optic nerve two types of macroglial cell were identified: astrocytes and oligodendroglia. Degeneration after injury proceeded rapidly in comparison with mammals but did not lead to the production of a dense scar. Before much scarring had developed, regenerating axons penetrated the lesioned area.

Use of the common carotid artery in blood pressure measurement in rats. A possible source of error

Comparison of blood pressures obtained by femoral and common carotid artery cannulation has shown that in the rat anaesthetized with Nembutal an increase in blood pressure occurs after neck surgery and common carotid artery cannulation.

Maternal phenylketonuria: abnormal baby despite low phenylalanine diet during pregnancy

During a screening programme of 10000 pregnant women by the Guthrie test, a previously unrecognised phenylketonuric woman was detected. A low phenylalanine diet introduced from the 16th week of gestation failed to prevent fetal abnormality and mental retardation. Maternal phenylketonuria requires earlier diagnosis than can be achieved at the initial antenatal clinic visit if its teratogenic effects are to be prevented.

Early events in stricture formation in the guinea pig urethra

The early stages of urethal stricture formation have been examined by light and electron microscopy after injury of the anterior urethra in the guinea pig. It was found that initially an ulcerated surface formed which was subsequently covered by simple then stratified squamous epithelium. The tissue of the stricture contained elongated myofibroblasts and clumps of multinucleated giant cells. It is suggested that the myofibroblasts are responsible for the formation of the stricture and that the giant cells may be involved in continued collagen synthesis.

Stool viruses in babies in Glasgow. 3. Community studies

Twenty-seven babies from one deprived housing area in Glasgow were followed-up regularly, for periods varying between 2 months and 11 months (mean 7 months), in a prospective study of the viruses to be found in their stools by electron microscopy. Weekly stool specimens were collected in the home together with a history of the baby's health. Additional stool specimens were obtained, up to a maximum of one per day, during admissions to hospital. Over 500 specimens were obtained at home and another 320 in hospital. A wide variety of viruses (over 200 recognizates) were detected and it has been possible to plot their temporal relation to disease episodes. It became apparent that virus excretion was frequently unaccompanied by evidence of illness and it has not been possible to describe a typical illness syndrome associated with any of the morphological types of virus observed. The results suggest that, in one area of Glasgow at least, patterns of virus excretion in young babies are complex and will need further elucidation before the need for a vaccine to prevent infantile diarrhoea could be defined.

An investigation into the hypothesis of shifting neuronal relationships during development

The projection of ganglion cells from the centre of the eye to the tectum has been followed during development in Xenopus by an autoradiographic technique. By comparing the caudal limit of this projection with a fixed line of cells labelled with tritiated thymidine the projection has been shown to shift caudally during development. This indicates a less rigid form of neuronal specificity than has previously been accepted.

The ultrastructure of human male urethral stricture

Biopsy material was examined from 20 urethral strictures at the time of urethroplasty, using ultramicroscopic methods not hitherto applied to the study of the pathogenesis of stricture. Abundant smooth muscle and elastic tissue was found in the post-inflammatory strictures. The scar tissue from post-traumatic strictures merely showed dense collagen. An anatomical basis for the well known difference between the fibrous and the resilent stricture is demonstrated, and the role of smooth muscle in the development and behaviour of strictures is discussed.

Degeneration of optic nerve terminals in the frog tectum

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The ultrastructure of ordinary and Purkinje cells of the fowl heart

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