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R Berry

Publications and source records attributed to R Berry.

At least 19 recordsLinked to original sources
PubMed1992

Carrier-like behaviour from a static but electrically responsive model pore.

Because of the low dielectric constant of most proteins and lipids, the electric field of an ion passing through a narrow pore is long range and will interact with neighbouring ionizable residues of the channel protein. The electrical structure of the channel may thus change transiently in response to an ion passing through the pore. Model calculations then reveal that the ratio of the unidirectional ion fluxes may approach 1 as expected for a carrier or shuttling ionophore rather than the Ussing ratio expected for a pore. Saturation behaviour also becomes carrier-like. Computer simulation is reported showing a continuous variation between pore-like and carrier-like behaviour as the parameters of the system are allowed to change smoothly.

Computer Simulation↗
PubMed1992

Regional and subcellular distribution of [125I]endothelin binding sites in rat brain.

The binding of [125I]endothelin-1 (125I-ET-1) to membranes from whole rat brain, from individual brain regions, and derived from subcellular fractionation of whole rat brain was investigated. 125I-ET-1 binding to whole rat brain membranes was rapid, concentration-dependent, saturable, and characterized as irreversible because it was not displaced by unlabeled endothelin-1 (ET-1) and different concentrations of ligand produced, with time, a similar magnitude of binding. The maximum binding site capacity and second-order forward rate association constant of binding were 1,946 +/- 147 fm/mg protein and 5.53 +/- 1.72 x 10(6) M-1 s-1. Removal of either extramembranal calcium or membrane-bound calcium and calcium binding proteins did not affect the binding of 125I-ET-1 to whole rat brain membranes. The brain stem and cerebellum contained the highest levels of 125I-ET-1 binding sites, whereas the cerebral cortex, striatum, and hippocampus contained binding site levels three- to fourfold less. Subcellular fractionation of whole rat brain and subsequent analyses of the distribution of 125I-ET-1 binding demonstrated a twofold enrichment of binding sites in the synaptosomal fraction compared to the homogenate. The myelin fraction contained a similar density of binding sites compared to the homogenate, while the mitochondrial and microsomal fractions contained considerably less binding sites. The ribosomal fraction did not contain any 125I-ET-1 binding sites. The subcellular distribution of 125I-ET-1 binding sites did not correlate with the distribution of 5'-nucleotidase, cytochrome-C oxidase, phosphodiesterase, and alkaline phosphatase. Depletion of extracellular calcium increased 125I-ET-1 binding in the synaptosomal fraction but not in the myelin and mitochondrial fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Cardiac responses and binding sites for endothelin in normal and cardiomyopathic hamsters.

The effects of endothelin-1 in the spontaneously beating atrium and the field-stimulated right ventricular strip preparation and the binding of [125I]endothelin-1 to membrane preparations from the atrium, ventricle, lung parenchyma, kidney and brain were compared using the 90-day-old dystrophic hamster strain CHF 147 (a strain displaying marked cardiomyopathologies at this age) and its age/genetically matched normal control, CHF 148. In the atrium, endothelin-1 produced dose-dependent positive inotropic and positive chronotropic effects in both CHF 148 and CHF 147 over the dose range of 10(-8) M to 3 x 10(-7) M. However, although no significant difference between CHF 148 and CHF 147 was observed for the positive chronotropic effects of endothelin-1, it produced a small, but significantly less positive inotropic effect in CHF 147 compared to CHF 148 at endothelin-1 concentrations of 2 x 10(-8) M and 3 x 10(-8) M. Field-stimulated right ventricular strips from CHF 148 contracted with a greater force compared to those from CHF 147. Endothelin-1 produced a dose-dependent decrease in the developed tension of the field-stimulated ventricular strip preparation, the extent of which did not differ between CHF 148 and CHF 147. [125I]Endothelin-1 bound with high affinity and in an apparently irreversible manner to membranes from both CHF 148 and CHF 147 atrium, ventricle, lung parenchyma, kidney and brain. No significant differences were noted between CHF 148 and CHF 147 for [125I]endothelin-1 binding to membranes prepared from the various tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Methods for studying the conductance changes associated with synaptic activation of forebrain slices: the interpretation of field potentials using CSD profiles.

In this report the cortical slice preparation and an array electrode that instantaneously records laminar field potentials are used to evaluate issues related to the interpretation of cortical CSD profiles. The major issues are: (1) what cell types are responsible for producing the source/sink pairs seen in CSD profiles; (2) what neurotransmitters are responsible for producing the sinks/sources seen in the CSD profile and do the sinks/sources reflect activation of receptors that produce inward currents, outward currents, or both; (3) can active and passive currents be distinguished; (4) do action potentials contribute to the CSD profile; and (5) can synaptic population with different kinetics and onset latencies be distinguished? Methods for analyzing neuronal circuits and analyzing CSDs quantitatively are discussed.

Animals↗
PubMed1990

Prohormonal cleavage sites are associated with omega loops.

Secretory peptides are generated from larger precursor proteins, or prohormones, by proteolytic cleavage at sites consisting of one or more basic amino acids. We have investigated the association of these cleavage sites with the various classes of secondary structure in the prohormones. In particular, we determined the association of cleavage sites with the newly defined category of omega loops. We developed an algorithm for predicting the occurrence of such loops from the primary structure of the precursor and validated this procedure by comparison to crystallographic data. When this method was applied to prohormones, we found that about one-third of the cleavage sites previously assigned to reverse turns were actually associated with omega loops. Moreover, sites that delimit secreted peptides are most often associated with loops and are concentrated in the neck regions of the loops. These data are interpreted in terms of a model in which the processing endoprotease interacts with two sites on the prohormone: a recognition site in the middle of a loop and the cleavage site at its neck.

Amino Acid Sequence↗
PubMed1990

Heterogeneity of acute "undifferentiated" leukemia of childhood: ultrastructural, immunophenotypic, and karyotypic analyses.

The present study was undertaken in an attempt to reclassify the 19 cases of childhood acute undifferentiated leukemia (AUL) diagnosed at our institution during the past 12 years. Based on ultrastructural and immunophenotypic data, seven of the cases were reclassified as lymphoid, nine as myeloid, and three remain unclassifiable. Clinical features, clonal karyotypes, and responses to treatment were also examined. Abnormal clonal karyotypes were found in 16 of 17 cases, including eight cases with translocations, three with monosomy 7 or 7q, and one with numerous complex structural rearrangements. Fourteen patients had greater than 10% French-American-British L2 blasts in bone marrow. Although nine of 15 patients who initially received induction therapy for acute lymphoblastic leukemia (ALL) achieved remission, only one patient is a long-term survivor. Only one of 10 patients who received therapy for acute nonlymphoblastic leukemia during the course of their disease remains a long-term survivor. These data suggest that the majority of cases of AUL can be reclassified as either myeloid or lymphoid leukemias, that AUL is associated with a high frequency of chromosomal abnormalities, and that AUL carries a very poor prognosis.

Adolescent↗
PubMed1990

Rehabilitation of children and infants with osteogenesis imperfecta. A program for ambulation.

Management of children and infants with osteogenesis imperfecta (OI) poses difficult decisions for pediatricians, orthopedists, and physiatrists. These children are frequently frail with disabling bone and joint deformities and fractures. In an eight-year cumulative management of 12 children with OI, a comprehensive program included strengthening exercises to the pelvic girdle and lower extremity muscles, in addition to pool exercises and molded seating to support upright posture. Long leg braces were fitted when the children were able to sit unsupported. All 12 were fitted with braces; nine were functional ambulators, and three were home ambulators. Six children required femoral plating or rodding, two of whom subsequently had the metal removed. Lower extremity fractures averaged one and one-half per year prior to bracing for nine children who had fractures. There was 0.83 fracture per year for the ten children who had fractures after bracing. The degree of femoral bowing increased in four, decreased in four, and remained unchanged in four, while the degree of tibial bowing increased in two, decreased in nine, and remained unchanged in one during the observation period. A comprehensive rehabilitation program and long leg bracing with surgical operations on the femur result in a high level of functional activity for children with OI with an acceptable level of risk for fracture.

Braces↗
PubMed1989

Apparent Smith-Lemli-Opitz syndrome and Miller-Dieker syndrome in a family with segregating translocation t(7;17)(q34;p13.1).

We describe a family in which one male infant presented with Miller-Dieker syndrome and four male relatives had a phenotype similar to the Smith-Lemli-Opitz (SLO) syndrome. High resolution cytogenetic analysis on the child with Miller-Dieker syndrome showed 46,XY,-17,+der17t(7;17)(q34:p13.1). Paternal chromosomes showed a balanced translocation: 46,XY,t(7;17)(q34:p13.1). The paternal grandmother had a history of multiple miscarriages, and a paternal uncle had two sons who died neonatally. Chromosomes on these children and their father had originally been reported as normal. There was also a paternal cousin to the father of the propositus who had had two sons with similar clinical findings. A diagnosis of SLO syndrome was considered. Image enhancement techniques on previous suboptimal preparations on these four children documented the subtle unbalanced translocation 46,XY,-7,+der7t(7;17)(q34:p13.1). Subsequent high resolution analysis on one of these four children who was still living confirmed this chromosome constitution. It is postulated that these apparent SLO cases may represent a contiguous gene syndrome in which SLO or a separate entity closely mimicking the syndrome in included.

Abnormalities, Multiple↗
PubMed1988

Institutional screening for the fragile X syndrome.

Cytogenetic screening of mentally retarded patients for the fragile X (fra[X]) chromosome is helpful in identifying individuals who could benefit from genetic counseling and treatment. Previous studies have demonstrated a prevalence of the fra(X) syndrome as high as 6% in institutionalized retarded males. The physical and behavioral predictors of positive findings from cytogenetic testing have not been clarified, since many features of the fra(X) syndrome are found in other retarded populations. We performed physical and cytogenetic examinations on 440 patients at the Wheat Ridge (Colo) Regional Center. Twenty-eight (6.3%) demonstrated abnormal karyotypes. Seventeen of these were autosomal abnormalities or sex chromosome aneuploidies and 11 demonstrated the fra(X) chromosome (seven males, four females). In males, the physical features that were predictive of the fra(X) syndrome included the combination of ear lengths of 7.0 cm or greater, macroorchidism of 30 mL or greater, and the presence of hand calluses or lesions secondary to hand biting. The fra(X) chromosome was not seen in spastic quadriplegic patients. All seven males with the fra(X) syndrome were detected among the 141 ambulatory males who resided in the highest functioning units at this institution.

Adolescent↗
PubMed1988

Linkage analysis using multiple DNA polymorphic markers in normal families and in families with fragile X syndrome.

Linkage data, using the polymorphic markers 52A (DXS51), F9, 4D-8 (DXS98), and St14 (DXS52), are presented from 14 fragile X pedigrees and from 7 normal pedigrees derived from the collection of the Centre d'Etude du Polymorphisme Humaine. A multipoint linkage analysis indicates that the most probable order of these four loci in normal families is DXS51-F9-DXS98-DXS52. Recombination frequencies (theta) corresponding to maximum LOD scores (Z) were obtained by two-point linkage analysis for a number of linkage groups, including: DXS51-F9 (Z = 5.94, theta = 0.03), F9-DXS98 (Z = 0.51, theta = 0.26), F9-DXS52 (Z = 0.84, theta = 0.27), and DXS98-DXS52 (Z = 0.32, theta = 0.20). A multipoint linkage analysis of these loci, including the fragile X locus, was also performed for the fragile X population and the data support the relative order (DSX51, F9, DXS98)-FRAXA-DXS52. Recombination frequencies and maximum LOD scores, which again were derived from two-point linkage analyses, were obtained for the linkage groups DXS51-F9 (Z = 9.96, theta = 0) and F9-DXS52 (Z = 0.07, theta = 0.45) as well as for the groups DXS51-FRAXA (Z = 2.42, theta = 0.15), F9-FRAXA (Z = 1.30, theta = 0.18), DXS98-FRAXA (Z = 0.05, theta = 0.36), and DXS52-FRAXA (Z = 2.42, theta = 0.15). The linkage data was further tested for the presence of genetic heterogeneity both within and between the fragile X and normal families for the intervals DXS51-F9, F9-DXS52, F9-FRAXA, and DXS52-FRAXA using a modification of the A test. Except for the interval F9-FRAXA (P less than 0.10) there was no evidence of genetic heterogeneity for each of the various linkage groups examined. The heterogeneity detected for the interval F9-FRAXA, however, was most likely due to one family (Fx-28) that displayed very tight linkage between these two loci.

Cells, Cultured↗
PubMed1986

Autism, mental retardation, and chromosomal abnormalities.

There are reports of sex chromosomal abnormalities including XXY, XYY, and fragile X karyotypes in autistic individuals, but structural autosomal defects have rarely been reported. This paper presents four patients with autism, mental retardation, minor dysmorphic features, and structural autosomal defects. These patients shared autistic features including fascination with inanimate objects, catastrophic reactions to changes in their environment or their daily routine, echolalia, and poor relatedness; IQ scores indicate mild to severe retardation. Their autosomal abnormalities included inversion/duplications of 3p and 16q, 5p+, and 17p-. Parental chromosomes were all normal. Chromosomal analysis should be performed on mentally retarded, autistic individuals, especially those with minor physical anomalies and no specific etiology for their retardation.

Adolescent↗
PubMed1986

MURCS association.

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Abnormalities, Multiple↗