A possibility of systematisation of anthropometric data of girls aged 12-15

The article describes an anthropometric cross-sectional study of 374 healthy schoolgirls aged 12-15 years from secondary schools of Tartu (Estonia). 29 body measurements and 9 skinfolds were measured. Mean skinfolds and 6 indices and ratios (including body mass index) were calculated. In each age group the data were systematized into 5 height-weight SD-classes according to the correspondence between body height and weight. The medium class lies between -0.5 SD and +0.5 SD of the respective age group mean (M +/- 0.5 SD); the other classes contain the respective outer values. All the subjects were assigned into one of the following five categories: three height/weight-concordant categories: I = small (small height-small weight), II = medium (medium height-medium weight), III = large (big height-big weight) and two height/weight-disconcordant categories: IV = so-called pyknomorphous, V = so-called leptomorphous. Categories IV and V thus contained three height/weight subclasses each. The body build categories differ significantly from each other within both groups (I-III and IV-V) in all age groups in all measured variables, except sternum length, abdomen length, trunk length, biacromial breadth, biiliocrystal breadth, femur breadth, ankle breadth, humerus breadth, wrist breadth, and head circumference for which no significant differences between pyknomorphous and leptomorphous categories were found. A multidimensional statistical model of body build might be used in girls going through puberty to systematize and compare morphological variables with other assessed characteristics in different applied studies, for example physiological, sociological, psychological, or nutritional.     

DNA fork displacement rates in synchronous aneuploid and diploid mammalian cells.

DNA fork displacement rates were measured in Chinese hamster ovary cells (CHO), human HeLa cells and human diploid fibroblasts. For CHO cells two independent techniques were used: one based on CsCl equilibrium density gradients and the other on 313 nm photolysis of incorporated bromodeoxyuridine (BrdUrd). Both methods indicated that there was no significant variation in fork displacement rates in CHO cells as they progressed through S phase. Asynchronous CHO cultures displayed the same average value (1.0 micron/min) and range of values as found in synchronous cells. In contrast, the rate of DNA fork displacement in HeLa cells, measured by the BrdUrd-313 nm method, increased continuously from 0.8 micron/min in early S to 2.5 micron/min in late S. For human diploid fibroblasts, in early S, the rate was approximately 0.7 micron/min and decreased to a minimum of 0.5 micron/min in mid S. The replication fork displacement rate then increased to a maximum of 0.9 micron/min in late S and declined again before the end of S phase. This pattern of DNA fork displacement rates roughly paralleled the overall thymidine incorporation rate and appears quite different from the patterns found for HeLa and CHO cells.     

A QTL for genotype by sex interaction for anthropometric measurements in Alaskan Eskimos (GOCADAN Study) on chromosome 19q12-13

Variation in anthropometric measurements due to sexual dimorphism can be the result of genotype by sex interactions (G×S). The purpose of this study was to examine the sex-specific genetic architecture in anthropometric measurements in Alaskan Eskimos from the Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) study. Maximum likelihood-based variance components decomposition methods, implemented in SOLAR, were used for G×S analyses. Anthropometric measurements included BMI, waist circumference (WC), waist/height ratio, percent body fat (%BF), and subscapular and triceps skinfolds. Except for WC, mean values of all phenotypes were significantly different in men and women (P < 0.05). All anthropometric measures were significantly heritable (P < 0.001). In a preliminary analysis not allowing for G×S interaction, evidence of linkage was detected between markers D19S414 and D19S220 on chromosome 19 for WC (logarithm of odds (lod) = 3.5), %BF (lod = 1.7), BMI (lod = 2.4), waist/height ratio (lod = 2.5), subscapular (lod = 2.1), and triceps skinfolds (lod = 1.9). In subsequent analyses which allowed for G×S interaction, linkage was again found between these traits and the same two markers on chromosome 19 with significantly improved lod scores for: WC (lod = 4.5), %BF (lod = 3.8), BMI (lod = 3.5), waist/height ratio (lod = 3.2), subscapular (lod = 3.0), and triceps skinfolds (lod = 2.9). These results support the evidence of a G×S interaction in the expression of genetic effects resulting in sexual dimorphism in anthropometric phenotypes and identify the chromosome 19q12-13 region as important for adiposity-related traits in Alaskan Eskimos.     

An immunocytochemical study of the distribution of pancreatic endocrine cells in chicks, with special reference to the relationship between pancreatic polypeptide and somatostatin-immunoreactive cells.

Araldite sections of formalin-fixed pancreas from chicks at hatching were treated by an indirect immuno-enzyme technique to reveal cells containing APP, somatostatin, glucagon and insulin. APP cells were found scattered in the exocrine parenchyma. A few were associated with insulin-containing B islets and occasional cells occurred in and around glucagon-containing A islets. Somatostatin-immunoreactive cells were distributed peripherally in A and B islets and were dispersed in the exocrine tissue. APP cells were roughly as numerous in the exocrine parenchyma as somatostatin-immunoreactive cells. Since certain published observations point to the possible occurrence of APP and somatostatin in the same cells, consecutive sections were stained for these hormones. In no case did the two peptides occur in the same cell. Sections subjected to double-staining confirmed this result. Therefore it is likely that the described differences between APP and somatostatin-immunoreactive cells are valid.     

An immunocytochemical study of the distribution of pancreatic endocrine cells in chicks,with special reference to the relationship between pancreatic polypeptide and somatostatin-immunoreactive cells

Summary Araldite sections of formalin-fixed pancreas from chicks at hatching were treated by an indirect immuno-enzyme technique to reveal cells containing APP, somatostatin, glucagon and insulin.APP cells were found scattered in the exocrine parenchyma. A few were associated with insulin-containing B islets and occasional cells occurred in and around glucagon-containing A islets. Somatostatin-immunoreactive cells were distributed peripherally in A and B islets and were dispersed in the exocrine tissue. APP cells were roughly as numerous in the exocrine parenchyma as somatostatin-immunoreactive cells.Since certain published observations point to the possible occurrence of APP and somatostatin in the same cells, consecutive sections were stained for these hormones. In no case did the two peptides occur in the same cell. Sections subjected to double-staining confirmed this result. Therefore it is likely that the described differences between APP and somatostatin-immunoreactive cells are valid.     

Quantitative morphological changes in endocrine pancreas of rats with spontaneous diabetes mellitus

The present study describes the cytopathology of the pancreatic islets in 18-old male eSS rats with spontaneous diabetes mellitus as compared to aged-matched normal animals. Light-microscopic immunocytochemical and morphometric techniques were used to study islet-cell populations, while quantitative methods were employed specifically for the analysis of B-cell ultrastructure. The diabetic rats showed disruption of the islet structure and fibrosis in the stroma. The volume density (Vvi) of endocrine tissue and the Vvi and percentage of B cells were diminished, whereas the Vvi of exocrine tissue and the Vvi and percentage of D cells were increased. The number of medium and large islets as well as their mean volume (micron3) decreased in these animals. Pancreatic B cells from eSS rats showed an increase in the Vvi of endoplasmic reticulum, immature secretory granules and lysosomes. Conversely, the Vvi of total secretory granules and microtubules appeared diminished. The current observations contribute to our understanding of this useful animal model of diabetes mellitus, in the attempt to clarify the pathogenesis of the disease.     

Immunocytochemical localization of muscarinic acetylcholine receptors in the rat endocrine pancreas

Summary Immunocytochemical application of the antimuscarinic acetylcholine receptor antibody M35 to pancreas tissue revealed the target areas for the parasympathetic nervous system. Immunoreactivity in the endocrine pancreas was much higher than that in the exocrine part. Moreover, the endocrine cells at the periphery of the islets of Langerhans displayed the highest level of immunoreactivity. Based on these findings in the mantle of the islets, two types of islets have been distinguished: type-I islets with intensely stained mantle cells, and type-II islets with a much lower concentration of these cells. On average, type-I islets were larger (244.8 m±6.1 SEM) than type-II islets (121.5 m±3.8 SEM). M35-immunoreactivity was present on the majority of D cells, which were characterized by their immunoreactivity to somatostatin [of 446 D cells 356 (79.8%) were M35-immunopositive]. However, only a small proportion of the intensely stained mantle cells belonged to the D cell population. Therefore, it is concluded that the majority of the intensely stained mantle cells represent glucagon-secreting A and/or pancreatic polypeptide-secreting F cells. The intensity of M35-immunoreactivity at the periphery and central core of the islets paralleled the density of cholinergic innervation, suggesting a positive correlation between the intensity of cholinergic transmission and the number of muscarinic acetylcholine receptors at the target structures. The present study further revealed some striking parallels for the muscarinic acetylcholine receptor characteristics between the (endocrine) pancreas and the central nervous system.     

Variations in enamel thickness and structure in East African hominids

Tooth fragments are an appreciable but neglected proportion of fossil hominid specimens. The present study on 47 naturally fractured enamel surfaces of premolar and molar teeth of Plio-Pleistocene East African hominids measured enamel thickness, slope of incremental lines (striae of Retzius), and the morphology of Hunter Schreger bands (HSBs). Specimens allocated to three categories--"robust" australopithecines (EAFROB), "early Homo" (EAFHOM), and "unknown"--were photographed in ethanol with polarised light. Enamel thickness was measured on the occlusal (OT), cuspal (CT), and lateral (LT) aspects. The angle of intersection of striae of Retzius (D) with the enamel-dentine junction (EDJ) was recorded, together with the degree of curvature and width of Hunter-Schreger bands (HSB). Absolute measurements of enamel thickness were scaled by using two allometry correction factors. Absolute thicknesses of all enamel measurements were significantly greater in the EAFROB (OT 3.1 mm; CT 3.3 mm; LT 2.4 mm) compared with EAFHOM (OT 1.4 mm; CT 1.6 mm; LT 1.6 mm) categories. Correction for size reduces the mean difference between the two taxa, but CT and OT thickness remain significantly different (P less than 0.05). HSBs in EAFROB were relatively straight and narrower (means = 52.8 micron) than in EAFHOM, which are more curved and wider (means = 62.0 micron), suggesting greater enamel prism decussation in early Homo. The slope of striae was less in EAFROB permanent molars (means = 23 degrees) compared with EAFHOM (means = 31 degrees), indicating faster rates of coverage during crown formation in "robust" australopithecines. We conclude that the study of fractured enamel surfaces can contribute to our understanding of the systematic relationships and patterns of enamel growth of early hominids.     

Heritability of anthropometric phenotypes in caste populations of Visakhapatnam,India

In this study, we used anthropometric data from six Andhra caste populations to examine heritability patterns of 23 anthropometric phenotypes (linear, craniofacial, and soft tissue measures) with special reference to caste differences. We obtained anthropometric data from 342 nuclear families from Brahmin, Reddy, Telaga, Nagara, Ag. Kshatriya, and Mala castes of Visakhapatnam, India. These caste groups represent the existing hierarchical stratification of Indian populations. We used a variance components approach to determine the heritability (h2) of these 23 anthropometric phenotypes (height, weight, BMI, etc.). The sample consisted of 1918 individuals ranging in age from 6 to 72 years (mean = 21.5, S.D. = 13.8). The heritabilities (h2 +/- S.E.) for all anthropometric traits for the entire sample were significant (p < 0.0001) and varied from 0.25 +/- 0.05 (BMI) to 0.61 +/- 0.05 (bizygomatic breadth) after accounting for sex, age, and caste effects. Since data on socioeconomic and nutritional covariates were available for a subset of families, we repeated the genetic analyses using this subset, which has yielded higher heritabilities ranging from 0.21 +/- 0.16 (head breadth) to 0.72 +/- 0.18 (nasal breadth). In general, craniofacial measurements exhibited higher h2 compared to linear measures. Breadth measurements and circumferences yielded more or less similar heritabilities. Age and sex effects were significant (p < 0.0001 ) for most of the traits, while the effects of caste, socioeconomic status, and nutritional status were inconsistent across the traits. In conclusion, anthropometric phenotypes examined in this study are under appreciable additive genetic influences.     

Diet breadth variability in larval blue whiting as a response to plankton size structure

Diet breadth (measured as the S.D. of the log of prey size per larvae; SLH) of blue whiting micromesistius poutassou larvae followed a quadratic equation with larval size. In small larvae, diet breadth in terms of size (SLH), the mean and the maximum of the log of prey size per larvae (MLH and XLH, respectively) increased with larval size as prey size selection shifted to larger prey. In contrast, large larvae tended to reduce diet breadth of prey sizes ingested, focusing on the larger prey that were abundant, instead of raising the upper limit of prey sizes because of the low abundance of larger prey. Except for larvae at the onset of first feeding, number of prey stayed constant or decreased in relation to larval size. Both patterns (in small and large larvae) maintained a constant rate of increase of gut carbon content with increase in larval size. Large larvae appear to maintain the increase in gut carbon content during ontogenetic development by reducing diet breadth (SLH) and increasing selection towards the larger prey that are abundant.     

Improved islet survival and in vitro function using solubilized small intestinal submucosa

In vitro proliferation of isolated pancreaticislets has become an area of great interest given the scarcity of clinicalisletdonors and the islet mass requirements for clinical islet transplantation.Smallintestinal submucosa (SIS), a naturally occurring extracellular matrix, hasbeeninvestigated to promote wound healing, tissue remodeling and cell growth. Thisstudy evaluated recovery and function of isolated canine pancreatic isletsfollowing in vitro tissue culture. Pancreatic islets wereisolated from mongrel dogs using standard surgical procurement followed byintraductal collagenase distension, mechanical dissociation and EuroFicollpurification. Groups of purified islets were cultured in a humidifiedatmosphereof 95% air and 5% CO₂ for 48 hours in standard islet cultureconditions of CMRL 1066 tissue culture media (Gibco) which had beensupplementedwith 25M HEPES, penicillin/streptomycin and either 10% heat inactivatedfetal calf serum (FCS, Gibco) or solubilized SIS solution (Cook Biotech, Inc.,West Lafayette, IN). The mean recovery of islets following the culture periodwas determined by sizing duplicate counts of a known volume and viability wasassessed by static incubation with low glucose (2.8 mM), highglucose (20 mM) and high glucose solution supplemented with 50m IBMX solution. Remaining islets were embeddedhistologically.From a consecutive series of six culture experiments, a significantly higher (p< 0.05) recovery of islets co-cultured with SIS was observed when comparedtocontrols. Mean islet recovery was 84.5 ± 2.9% (mean ± SEM) fromthe SIS cultured group compared with 64.7 ± 4.5% from the control groupcultured in FCS (p < 0.05, n=6). Islets from the SIS treated group exhibiteda significantly higher (p <, 0.05) insulin response to the high glucosestimulus than islets cultured in the standard FCS cultured solution. Thecalculated stimulation index was 12.3 ± 3.4 for the SIS-treated groupcompared with 5.6 ± 1.8 for the standard cultured group (p < 0.05).The overall mean numbers of islets recovered following invitro culture was also higher in the SIS-treated group. Theproportion of islets with a mean diameter >150 m increasedfrom 24% to 31% in the SIS-treated group, whereas the same proportion decreasedto 18% from 22% in the control (FCS-treated) group. Histological evaluation offixed tissue samples collected following the culture period identified insulinand glucagon-secreting cells in the SIS and FCS treated groups, however ahigherfrequency of insulin positive cells were detected consistently in the SIStreated group. A proliferation marker (PCNA) identified positive cells withinboth groups as well. This study suggests that co-culture of freshly isolatedcanine islets in medium supplemented with solubilized SIS can improve thepost-culture recovery and in vitro islet function. Futureinvestigations will focus on the cellular interactions of SIS, bothinvitro and in vivo.     

Lethal action of accelerated heavy ions on mammalian cells as affected by inhibitors of DNA synthesis. Results of experimental research

Radiosensitivity of Chinese hamster cells exposed to 137Cs-gamma-radiation and accelerated heavy ions of 4He (L = 22 and 60 keV/micron), 12C (L = 231 keV/micron), and 20Ne (L = 690 keV/micron) was studied in standard conditions and in the presence of arabinosylcytosine and hydroxyurea. These agents were shown to exert a radiosensitizing effect in the case of gamma-radiation. The effect was less pronounced with 4He ion-radiation and was absent upon irradiation with 12C and 20Ne ions. The radiosensitivity was maximum upon irradiation with 4He ions at L = 60 keV/micron. The RBE coefficients of heavy ions under study decreased in the presence of DNA synthesis inhibitors.     

Effect of cell substratum on lateral mobility of lipids in the plasma membrane of vascular endothelial cells

Bovine vascular endothelial cells can be maintained in a highly differentiated state in vitro, either by the addition of fibroblast growth factor (FGF) to the culture medium or by plating the cells on extracellular matrix (ECM)-coated dishes. Under these conditions the cells proliferate actively and at confluence form a tightly packed monolayer composed of nonoverlapping polarized cells. A fluorescence recovery after photobleaching method was used to determine the lateral mobility coefficient D of the lipophilic fluorescent probe, 5N-(hexadecanoyl)-aminofluorescein (HEDAF), in the basal and apical plasma membranes of endothelial cells under various culture conditions (cells on glass coverslips in the presence or absence of FGF, or cells plated on ECM in the exponential growth phase or at confluence). A heterogeneous distribution of lateral diffusion coefficients D was found in a given cell population. Nevertheless, for the basal membrane, a "mean" D value close to 2.0 x 10(-9) cm2/s was found for all the culture conditions. The "mean" D value of HEDAF in the apical pole was slightly higher when sparse cells were exposed to FGF (D = 2.2 x 10(-9) cm2/s) and was further enhanced when cells were growing or confluent on ECM-coated coverslips (D = 2.7 x 10(-9) cm2/s). On the other hand, when the cells were maintained in the absence of FGF on glass coverslips, similar "mean" D values were found in both cell poles (D = 2.0 x 10(-9) cm2/s). These results show that lateral mobility of lipids in endothelial plasmalemma varies in response to external factors such as FGF and the ECM.     

The ultrastructural basis for the identification of cell types in the pancreatic islets

Summary The pancreatic islets of rabbit, dog and opossum have been studied by light and electron microscopy. Silver-positive cells in the rabbit are predominantly sandwiched between the peripheral A and central B cells, and by electron microscopy are identified as D cells. Pancreatic islets in the tail of the dog pancreas have A, B, and D (silver-positive) cells, but the islets in the uncinate process of the dog pancreas lack phosphotungstic acid hematoxylin-positive A cells. By electron microscopy the characteristic D cells are found in both tail and uncinate process, but A cells are confined to the tail islets, confirming the identification of cell types. A unique cell type termed the F cell is found in the dog uncinate islets and it is characterized by secretory granules of angular profiles. In the opossum, the A cells contain considerable amounts of glycogen demonstrable by both light and electron microscopy. A unique cell type is also present in the opossum islets termed an E cell (Thomas, 1937), which has large secretory granules (400–500 m). The physiological implications of a multiplicity of cell types in pancreatic islets is discussed.This investigation was supported in part by United States Public Health Service research grants GM-10102 and GM-03784 from the Institute of General Medical Sciences, and AM-01226 from the Institute of Arthritis and Metabolic Diseases. The authors wish to acknowledge the valuable technical assistance of Mrs. Aileen Sevier and Mrs. Lidia Donahue.     

Highly sensitive sites for guanine-O6 ethylation in rat brain DNA exposed to N-ethyl-N-nitrosourea in vivo.

Brain chromosomal DNA isolated from fetal BDIX-rats 1 h after i.v. administration of the ethylating N-nitroso carcinogen N-ethyl-N-nitrosourea (75 micrograms/g body weight), statistically contained one molecule of O6-ethyl-2'-deoxyguanosine (O6-EtdGuo) per 81 micron of DNA, as determined in enzymatic DNA hydrolysates by competitive radio-immunoassay using a high-affinity anti-(O6-EtdGuo) monoclonal antibody (ER-6). After fragmentation of the DNA by the restriction enzyme AluI (average fragment length, Lav = 0.28 micron = 970 bp; length range, Lr = 1.87-0.02 micron = 6540 - 60 bp), a small (approximately 2%) fraction of DNA enriched in specific polypeptides tightly associated with DNA was separated from the bulk DNA by a glass fiber binding technique. As analyzed by immune electron microscopy, approximately 1% of the DNA molecules in this fraction contained clusters of 2-10 (O6-EtdGuo)-antibody binding sites (ABS). On the cluster-bearing fragments (Lav, 0.85 micron +/- 0.50 micron S.D.; corresponding to 2970 +/- 1760 bp) the average ABS-ABS interspace distance was 110 nm (= 390 bp; range approximately 9-600 nm), indicating a highly non-random distribution of O6-EtdGuo in target cell DNA.     

Proliferation and differentiation sequence of osteoblast histogenesis under physiological conditions in rat periodontal ligament

To define the mechanism of osteoblast histogenesis, nuclear morphometry was utilized as a marker for precursor cell differentiation. One hour after 3H-thymidine injection, groups of 7-week-old rats were killed at hourly intervals over one complete 24-hr photoperiod (LD 12:12). S-phase and mitosis were assessed in autoradiographs of 3-micron sections of molar periodontal ligament (PDL) adjacent to a physiological bone-forming surface. Labeled nuclei were divided into four categories according to morphometry of nuclear size: A (40-79 micron3), B (80-119 micron3), C (120-169 micron3), and D (greater than or equal to 170 micron3) cells. C and D cells synthesize DNA during the light and divide in the following dark phase; the rhythm for A cells is the opposite. B cells demonstrated no preference and were subsequently determined to be nonosteogenic. Compared to A cells the S-phase photoperiod of C and D cells (combined) is approximately a one-to-one reciprocal relationship, suggesting two proliferating progenitors in series. Based on arrest points in the histogenesis sequence, five compartments are defined: 1) A cells, less differentiated, self-perpetuating precursors; 2) A' cells, committed osteoprogenitors; 3) C cells, G1 stage preosteoblasts; 4) D cells, G2 stage preosteoblasts; and 5) Ob cells, morphologically distinct osteoblasts. Minimal elapsed time for the A----A'----C----D----Ob sequence is about 60 hr (five alternating dark/light cycles). A stress/strain-mediated increase in nuclear volume (A'----C) is an important, rate-limiting step in osteoblast differentiation.     

An immunohistochemical study of the insulin-, glucagon- and somatostatin-immunoreactive cells in the developing pancreas of the chicken embryo

The distributions and relative frequencies of insulin-, glucagon- and somatostatin-immunoreactive cells were studied in dorsal, ventral, third and splenic lobes of developing chicken pancreas during embryonic periods (10 days of incubation to hatching) by immunohistochemical methods. The regions of pancreas were subdivided into three regions: exocrine, light and dark islet. Round, oval and spherical shaped immunoreactive cells were detected in all four lobes. According to developmental stages, the types of lobes and the regions of pancreas showed various distributions and relative frequencies. In the splenic lobes, insulin, glucagon and somatostatin-immunoreactive cells were detected in exocrine, dark islet and light islet from time differentiation of splenic lobes, 13 days of incubation. The insulin- and somatostatin-immunoreactive cells of the third lobes were detected in exocrine and light islets from 10 days of incubation, and in dark islets from 15 and 11 days of incubation respectively. Glucagon-immunoreactive cells were detected in exocrine, dark and light islets from 16, 11 and 19 days of incubation respectively. These immunoreactive cells of the ventral lobes were detected in exocrine and light islets. However, dark islets were not found in this lobe. Insulin-immunoreactive cells were demonstrated from 10 days of incubation in these two regions. Glucagon-immunoreactive cells were detected from 17 days of incubation in exocrine and 16 days of incubation in the light islets. Somatostatin-immunoreactive cells were demonstrated from 11 days of incubation in exocrine and 14 days of incubation in the light islets. In the dorsal lobes, insulin-immunoreactive cells were demonstrated in exocrine, dark and light islets from 12, 14, and 13 days of incubation, respectively. Glucagon- and somatostatin-immunoreactive cells were detected in dark and light islets from 13 and 14 days of incubation, respectively. Glucagon- and somatostatin-immunoreactive cells were demonstrated from 10 and 11 days of incubation in exocrine respectively. Generally, insulin-immunoreactive cells were increased in light islets but decreased in light islets with developmental stages. However, glucagon-immunoreactive cells were decreased in light islets but increased in dark islets. In addition, somatostatin-immunoreactive cells showed the same frequencies in light and dark islets with developmental stages except exocrine which increased with developmental stages.     

Pancreatic APUD cells in older chick embryos,with special reference to their identity

Summary Pancreatic APUD cells showing formaldehyde-induced fluorescence in Black Australorp chick embryos of nine to eighteen days of incubation, proved, on subsequent staining and silver impregnation, to be A, B, D and, from sixteen days, enterochromaffin (EC) cells. EC and D cells were scattered in the exocrine parenchyma, the latter cells increasing with time. Some groups of B cells were associated with large A islets from the ninth day of incubation onwards. The composition of A islets (A and some D cells) and B islets (B and some D cells) and the distribution attained (A islets in the splenic and third lobes; B islets in all lobes), accords with the situation reported for adults.     

Quantitative ultrastructural study of nucleolus-organizing regions at some stages of the cell cycle (G0 period, G2 period, mitosis)

The quantitative characteristics of chromosomal nucleolus-organizing regions (NORs) and some other nucleolar components were studied on ultra-thin sections of pig embryo kidney cells (PK cells). It was shown that: 1) nucleoli-per-cell volumes were 3 times smaller in the G0 period than in the G2 period; 2) the number of fibrillar centers (FCs) per cell in the G0 period, the G2 period, and at metaphase was equal to 7, 33.7, and 8, respectively; 3) mean volumes of individual FCs in the G0 period (0.033 +/- 0.005 micron3), G2 period (0.014 +/- 0.001 micron3), and at metaphase (0.025 +/- 0.002 micron3) were significantly different; 4) the total volumes of FCs calculated per haploid set of chromosomes were practically the same in the G0 (0.105 micron3) and G2 (0.107 micron3) periods, but were twice as large as those at metaphase (0.04-0.05 micron3). These data show that partial activation and inactivation of ribosomal genes in interphase PK cells are not accompanied by a considerable change in the total volume of FCs and may be due to the fragmentation and fusion of individual FCs. Complete inactivation of ribosomal genes in mitosis results in a decrease of total volumes of FCs per cell; 5) in G0 and G2 periods the total volume of the dense fibrillar component per nucleolus is practically proportional to the nucleolus volume (r = 0.99); 6) in the G2 period, the nucleolus volume is also proportional to the number of FCs (r = 0.99; 7) the volume of the dense fibrillar component within individual fibrillar complexes is not a constant one.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dominant intermediate Charcot-Marie-Tooth neuropathy maps to chromosome 19p12-p13.2

The hereditary disorders of peripheral nerve form one of the most common groups of human genetic diseases, collectively called Charcot-Marie-Tooth (CMT) neuropathy. Using linkage analysis we have identified a new locus for a form of CMT that we have called "dominant intermediate CMT" (DI-CMT). A genomewide screen using 383 microsatellite markers showed strong linkage to the short arm of chromosome 19 (maximum LOD score 4.3, with a recombination fraction (straight theta) of 0, at D19S221 and maximum LOD score 5.28, straight theta=0, at D19S226). Haplotype analysis performed with 14 additional markers placed the DI-CMT locus within a 16.8-cM region flanked by the markers D19S586 and D19S546. Multipoint linkage analysis suggested the most likely location at D19S226 (maximum multipoint LOD score 6.77), within a 10-cM confidence interval. This study establishes the presence of a locus for DI-CMT on chromosome 19p12-p13.2.