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Biomedical subjects

H Green

Publications and source records attributed to H Green.

At least 73 records · Page 4Linked to original sources
PubMed1995

Failure of short term stimulation to reduce sarcoplasmic reticulum Ca(2+)-ATPase function in homogenates of rat gastrocnemius.

To examine the effect of short term intense activity on sarcoplasmic reticulum (SR) Ca2+ sequestering function, the gastrocnemius (G) muscles of 11 anaesthetized male rats (weight, 411 +/- 8 g, X +/- SE) were activated using supramaximal, intermittent stimulation (one train of 0.2 msec impulses per sec of 100 msec at 100 Hz). Homogenates were obtained from stimulated white (WG-S) and red (RG-S) tissues, assayed for Ca2+ uptake and maximal Ca2+ ATPase activity and compared to contralateral controls (WG-C, RG-C). Calcium uptake (nmoles/mg protein/min) determined using Indo-1 and at [Ca2+]i concentrations between 300-400 nM was unaffected (p > 0.05) by activity in both WG (6.14 + 0.43 vs 5.37 + 0.43) and RG (3.21 + 0.18 vs 3.07 + 0.20). Similarly, no effect (p > 0.05) of contractile activity was found for maximal Ca2+ ATPase activity (mumole/mg protein/min) determined spectrophotometrically in RG (0.276 + 0.03 vs 0.278 + 0.02). In WG, Ca2+ ATPase activity was 15% higher in WG-S compared to WG-C (0.412 + 0.03 vs 0.385 + 0.04). Repetitive stimulation resulted in a reduction in tetanic tension of 74% (p < 0.05) by 2 min in the G muscle. By the end of the stimulation period, ATP concentration was reduced (p < 0.05) by 57% in the WG and by 47% in the RG.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗
PubMed1995

Origin of the polymorphism of the involucrin gene in Asians.

The involucrin gene, encoding a protein of the terminally differentiated keratinocyte, is polymorphic in the human. There is polymorphism of marker nucleotides a two positions in the coding region, and there are over eight polymorphic forms based on the number and kind of 10-codon tandem repeats in that part of the coding region most recently added in the human lineage. The involucrin alleles of Caucasians and Africans differ in both nucleotides and repeat patterns. We show that the involucrin alleles of East Asians (Chinese and Japanese) can be divided into two populations according to whether they possess the two marker nucleotides typical of Africans or Caucasians. The Asian population bearing Caucasian-type marker nucleotides has repeat patterns similar to those of Caucasians, whereas Asians bearing African-type marker nucleotides have repeat patterns that resemble those of Africans more than those of Caucasians. The existence of two populations of East Asian involucrin alleles gives support for the existence of a Eurasian stem lineage from which Caucasians and a part of the Asian population originated.

Alleles↗
PubMed1994

Codon reiteration and the evolution of proteins.

Sequence data banks have been searched for proteins possessing uninterrupted reiterations of any amino acid. Hydrophilic amino acids, and particularly glutamine, account for a large proportion of the longer reiterants. In the genes for these proteins, the most common reiterants are those that contain poly(CAG), even out-of-frame or, to a lesser degree, those that contain repeated doublets of CA, AG, or GC. The preferential generation of such reiterants requires that DNA strand-specific signals predispose to reiteration and thus to the extension of coding regions.

Amino Acid Sequence↗
PubMed1994

Association of basonuclin with ability of keratinocytes to multiply and with absence of terminal differentiation.

Basonuclin is a protein possessing three pairs of zinc fingers and a nuclear localization signal. Expression of the gene is largely confined to keratinocytes of stratified squamous epithelia and hair follicles. In the epidermis and in stratified epidermal cultures, basonuclin is present in the nuclei of cells in or close to the basal layer but not in the nuclei of cells in more superficial layers. The Ki-67 protein, a nuclear marker for any stage of the multiplication cycle is present in only a subclass of basonuclin-containing cells. In cultured keratinocytes, the disappearance of basonuclin mRNA is associated with loss of colony-forming ability and the appearance of mRNA for involucrin, a protein characteristic of terminal differentiation. In hair follicles, the largest reservoir of basonuclin-containing cells is the outer root sheath, which contains precursors of differentiated cells of the hair shaft and of the epidermis. Basonuclin is not a cell cycle marker but is likely instead to be a regulatory molecular whose presence in the keratinocyte is linked to the maintenance of proliferative capacity and prevention of terminal differentiation.

Adult↗
PubMed1993

The involucrin genes of the mouse and the rat: study of their shared repeats.

The involucrin genes of the mouse (Mus musculus) and the rat (Rattus norvegicus) have been cloned and sequenced. The coding region of each gene contains, at site P, a segment of repeats homologous to that of other nonanthropoid mammals. In contrast to the repeats of species belonging to different mammalian orders, many individual repeats of the mouse and the rat can be matched. Both before and after the divergence of the two species, these repeats have been the site of systematic alterations in nucleotide sequence. One of the alterations is the correction of nucleotides of one repeat by those of another. Corrected nucleotides may be closely linked to flanking nucleotides that are uncorrected; the systematic correction process therefore appears to be due to gene conversion. There is a stretch of 18 reiterated CAGs in the segment of repeats of the Mus gene; most of these reiterations were introduced recently, supporting the idea that the gene was generated originally from poly CAG. An antiserum to a synthetic peptide encoded by the segment of repeats of the Mus gene reveals differentiation-specific expression of the gene in the epidermis.

Animals↗
PubMed1993

Nortriptyline-induced depression of ventilatory control in a patient with chronic obstructive pulmonary disease.

Psychiatric disorders occur frequently in patients with COPD, but therapy with psychotropic drugs is often limited by concomitant depression of ventilatory drive. We present a patient with COPD and major depression who developed hypercapnic respiratory failure while receiving nortriptyline and oxazepam. Because of known respiratory depressant effects of the latter drug, nortriptyline alone was resumed upon recovery. Depression of CO2 sensitivity and ventilatory load compensation with a concomitant increase in exercise tolerance with decreased dyspnea was observed while she was receiving nortriptyline. These results demonstrate a previously unreported depressant effect of nortriptyline on ventilatory control, and they suggest the need for further investigation of the ventilatory effects of this drug in patients with pulmonary disease.

Aged↗
PubMed1992

Basonuclin: a keratinocyte protein with multiple paired zinc fingers.

A cDNA clone has been prepared from mRNA of cultured human keratinocytes. The sequence of the cDNA reveals that in the C-terminal two-thirds of the corresponding protein (basonuclin), there are three separated pairs of adjacent zinc fingers. The amino acid sequence of each pair is homologous to that of the single pair of zinc fingers of the Drosophila transcription factor encoded by disco. Near the C-terminal end of basonuclin and on the surface of a putative alpha-helix, there is a stripe of serine residues similar to that of the transcription factor PRDII-BF1. Basonuclin possesses a sequence of six amino acids quite similar to one present in the myogenic family of proteins, including Myf5; this sequence is located in the omega loop of the myogenic proteins but within a zinc finger of the keratinocyte protein. As basonuclin is present mainly in the nuclei of the basal cell layer, its regulatory function is likely to be exerted prior to the process of terminal differentiation.

Amino Acid Sequence↗
PubMed1992

The involucrin gene of Old-World monkeys and other higher primates: synapomorphies and parallelisms resulting from the same gene-altering mechanism.

The involucrin gene of platyrrhines and hominoids contains a segment of 10-codon repeats which were added vectorially at the same site in the coding region. We have now cloned and sequenced the involucrin gene of four cercopithecoid monkeys--two macaques (mulatta and fascicularis) and two Cercopithecus monkeys (aethiops and hamlyni). Each gene contains a similar segment of short repeats; some of these were added in a common anthropoid lineage, others were added in a common catarrhine lineage, and still others were added in a common macaque or Cercopithecus lineage. Repeats added before a lineage diverges become synapomorphies in the sister taxa resulting from the divergence. Repeats added independently in different diverged lineages become parallelisms. The synapomorphies are the result of the action of a targeted duplication mechanism acting in a common ancestral lineage, but the parallelisms are the result of the same duplication mechanism transmitted to successively divergent sublineages and acting independently in each.

Alleles↗
PubMed1992

Consecutive actions of different gene-altering mechanisms in the evolution of involucrin.

During the evolution of primates from nonprimates, the gene for involucrin was greatly altered by changes in the short tandem repeats that are present in some form in the gene of each of 17 species examined. The evolution of involucrin was not the result of a single continuum of more or less random changes, and it was not confined to the process of nucleotide substitution, the most commonly studied evolutionary change in DNA. Instead, the evolution of this gene took place through different mechanisms that shortened the length of the repeats, increased their number, and changed their codon sequence. As part of this trend, one entire segment of repeats was replaced by another located elsewhere in the coding region. To bring about these changes, specific mechanisms have been activated, deactivated, and replaced by other mechanisms. The resulting serial revisions in the involucrin gene must depend on gene-altering machinery whose synthesis or activity can be controlled.

Amino Acid Sequence↗
PubMed1991

Involucrin gene of tarsioids and other primates: alternatives in evolution of the segment of repeats.

The involucrin genes of the prosimian primates and of the anthropoid primates possess nonhomologous segments of repeats located at two different sites, P and M, within the coding region. The involucrin gene of the tarsioids alone contains repeats at both sites, for it derived repeats at site P from a common ancestor of tarsioids and prosimians and a repeat at site M from a later common ancestor of tarsioids and anthropoids. After their divergence from the tarsioids, the anthropoids added many more repeats to site M and excised the older segment of repeats from site P; in contrast, the tarsioids stopped adding repeats at site M, retained the earlier segment of repeats at site P, and enlarged it. In the revision of their involucrin genes, the two lineages followed alternative routes. The mechanisms by which the revisions took place have been subject to abrupt onset or termination.

Animals↗
PubMed1991

Golgi apparatus of epithelial principal cells of the epididymal initial segment of the rat: structure, relationship with endoplasmic reticulum, and role in the formation of secretory vesicles.

The initial segment of the epididymis of rats, fixed with glutaraldehyde, was postfixed with reduced osmium, a technique that clearly delineates the membranes of cisternae of the endoplasmic reticulum (ER) and the various elements of the Golgi apparatus, or with tannic acid to enhance the coats of vesicles and ribosomes on ER cisternae. The material was also treated to demonstrate various phosphatase activities (NADPase, TPPase, CMPase, G-6-Pase) or impregnated with osmium tetroxide. In osmium-impregnated material, the Golgi apparatus of the epithelial principal cells of the initial segment appeared in the light microscope as a branching, anastomosing ribbon forming a large network in the supranuclear region. In the electron microscope, ER were of two types: the heavily granulated, flattened, rough ER seen in the infranuclear and juxtanuclear regions and the distended, tubular, sparsely granulated ER, showing only few ribosomes, seen interlaced with the Golgi ribbon in the supranuclear region and at the apical pole of the cell. Of particular interest in this cell was the fact that the sparsely granulated ER approximated the Golgi stack on both its cis- and trans-faces. On the cis-face of the Golgi stack, the sparsely granulated ER cisternae showed the usual finger- or bud-like protrusions directed toward the cis element of the Golgi stack and around which numerous small 80 nm vesicles or membranous tubules were clustered. The Golgi stack consisted of the following elements in a cis-trans axis: the cis osmiophilic element, a first saccule slightly dilated, saccules two to four (S2-S4), which were NADPase-positive, and saccules five to seven and the eight Golgi element, which were TPPase-positive. On the trans-aspect of the Golgi stacks, several (up to four) CMPase-positive trans-Golgi networks were observed often in close apposition to the sparsely granulated ER cisternae. One of the trans-Golgi networks showed a "peeling-off" configuration, i.e. part of it was closely apposed to the overlying Golgi element of the stack, whereas the remaining part was separated from the stack by a space occupied by a cisterna of sparsely granulated ER. The other trans-Golgi networks were completely separated from the stack and were often seen sandwiched between sparsely granulated ER cisternae. Thus, ER cisternae showed extensive areas of close apposition but no continuity with the trans-Golgi networks. Although the saccules of the Golgi stacks showed NADPase and/or TPPase activity, the trans-Golgi networks displayed CMPase activity, thus facilitating their identification from the closely associated unreactive sparsely granulated ER cisternae.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Polymorphism due to variable number of repeats in the human involucrin gene.

The coding region of the involucrin gene in higher primates contains a segment consisting of numerous tandem repeats of a 10-codon sequence. The process of repeat addition began in a common ancestor of all higher primates and subsequent repeats were added vectorially. As a result, the principal site of repeat addition has moved in the 3' to 5' direction and the most recently generated repeats (the late region) are close to the 5' end of the segment of repeats. In the human, most of the late region is made up of two different blocks, each consisting of nearly identical repeats. We describe here five polymorphic forms resulting from the addition of differing numbers of repeats to each block. As the variety and nature of the polymorphic alleles are different in different human populations, we postulate that the process of repeat addition is genetically determined.

Alleles↗
PubMed1991

The involucrin genes of the white-fronted capuchin and cottontop tamarin: the platyrrhine middle region.

In all anthropoid species, the coding region of the involucrin gene contains a segment of short tandem repeats that were added sequentially, beginning in a common anthropoid ancestor. The involucrin coding region of each of two platyrrhine species, the white-fronted capuchin (Cebus albifrons) and the cottontop tamarin (Saguinus oedipus), has now been cloned and sequenced. These genes share with the genes of the catarrhines the repeats added in the common anthropoid lineage (the early region). After their divergence, the platyrrhines, like the catarrhines, continued to add repeats vectorially 5' of the early region, to form a middle region. The mechanism that was established in the common anthropoid lineage for the addition of repeats at a definite site in the coding region was transmitted to both platyrrhines and catarrhines, enabling each to generate its middle region independently. The process of vectorial repeat addition continued in two platyrrhine sublineages after their divergence from each other.

Animals↗