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Biomedical subjects

A Avni

Publications and source records attributed to A Avni.

At least 37 records · Page 2Linked to original sources
PubMed1990

Poliomyelitis outbreak in Israel in 1988: a report with two commentaries.

An outbreak of 15 cases of paralytic poliomyelitis caused by type 1 poliovirus between July and October, 1988, prompted mass vaccination of the whole Israeli population under the age of 40 years. The focus of the outbreak (12 cases) was the Hadera subdistrict, one of two subdistricts where enhanced inactivated poliovaccine (eIPV) had been the only poliovaccine used for infants since 1982. 9 of the 15 victims were 15 years or older, and 9 had previously been immunised with at least three doses of oral poliovaccine (OPV). The authors are divided in their interpretation of the findings. One group considered that the likely causative factors were the greater susceptibility of young adults previously vaccinated with OPV as well as transmission of wild poliovirus to susceptible people by children with low gut immunity against poliovirus after vaccination with eIPV; they concluded that a vaccination programme combining eIPV with OPV is the best option for Israel in future. The other group believed the causative factors were exposure to contaminated sewage or close social contact within the epidemic foci, the presence of an epidemic strain differing from the wild Mahoney and Sabin type 1 vaccine strains, and the lower seropositivity rates and geometric mean titres of neutralising antibodies to the epidemic than to vaccine strains; they believe that eIPV is the means to achieve effective control of poliomyelitis in Israel.

Adolescent↗
PubMed1989

A point mutation in the gene for the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase affects holoenzyme assembly in Nicotiana tabacum.

In photosynthetic eukaryotes, the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is composed of eight large and eight small subunits. Chloroplast-coded large subunits are found in association with chaperonins (binding proteins) of 60-61 kd to form a high mol. wt pre-assembly complex (B-complex). We have isolated a heterotrophic, maternally-inherited mutant from Nicotiana tabacum var. Xanthi which accumulates the B-complex but contains no Rubisco holoenzyme. The B-complex of the mutant dissociates in the presence of ATP, as does that of the wild-type. Processing of the nuclear-coded small subunit takes place in the mutant and neither large nor small subunits accumulate. The large subunit gene from mutant and wild-type plants was cloned and sequenced. A single nucleotide difference was found between them predicting an amino acid change of serine to phenylalanine at position 112 in the mutant. Based on the resolved structure of N.tabacum Rubisco, it is argued that the alteration at position 112 prevents holoenzyme assembly by interfering with large subunit assembly.

Amino Acid Sequence↗
PubMed1985

A human acetylcholinesterase gene identified by homology to the Ace region of Drosophila.

The Ace locus of the Drosophila genome controls biosynthesis of the neurotransmitter-hydrolyzing enzyme acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7). We injected the mRNA species hybridizing with DNA fragments from this region into Xenopus oocytes, in which acetylcholinesterase mRNA is translated into active acetylcholinesterase. A 2.0-kilobase (kb) fragment of DNA from this region selectively hybridizes with Drosophila mRNA capable of inducing the biosynthesis of acetylcholinesterase in oocytes. This Drosophila DNA fragment cross-hybridized with human brain poly(A)+ RNA. We therefore used this DNA fragment as a probe for homologous sequence(s) in a human genomic DNA library and thus selected a 13.5-kb human DNA segment. DNA blot-hybridization revealed that a 2.6-kb fragment of this human DNA segment hybridizes with the Drosophila 2.0-kb DNA fragment. Both Drosophila and human fragments hybridized with a human brain mRNA species of about 7.0-kb that was barely detectable in the acetylcholinesterase-deficient HEp carcinoma. A fraction containing mRNA of similar size, extracted from human brain, induced acetylcholinesterase biosynthesis in oocytes. The human DNA fragment also was used in hybridization-selection experiments. In oocytes, hybrid-selected human brain mRNA induced acetylcholinesterase activity that was completely inhibited by 1,5-bis[4-allyldimethylammonium)phenyl]pentan-3-one dibromide but not by tetraisopropyl pyrophosphamide, a differential response to these inhibitors characteristic of "true" human brain acetylcholinesterase. These findings strongly suggest that both the Drosophila and the human DNA fragments are directly involved in controlling acetylcholinesterase biosynthesis.

Acetylcholinesterase↗
PubMed1985

Polymorphism of acetylcholinesterase in discrete regions of the developing human fetal brain.

The molecular forms and membrane association of acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) and pseudocholinesterase (acylcholine acylhydrolase, EC 3.1.1.8) were determined in the presence of protease inhibitors in dissected regions of developing human fetal brain, as compared with parallel areas from mature brain. All areas contained substantial cholinesterase activities, of which acetylcholinesterase accounted for almost all the activity. Two major forms of acetylcholinesterase activity, sedimenting at 10-11S and 4-5S, respectively, were detected on sucrose gradients and possessed similar catalytic properties, as judged by their individual Km values toward [3H]acetylcholine (ca. 4 X 10(-4) M). The ratio between these forms varied by up to four- to fivefold, both between different areas and within particular areas at various developmental stages, but reached similar values (about 5:2) in all areas of mature brain. Acetylcholinesterase activity was ca. 35-50% low-salt-soluble and 45-65% detergent-soluble in various developmental stages and brain areas, with an increase during development of the detergent-soluble fraction of the light form. In contrast, pseudocholinesterase activity was mostly low-salt-soluble and sedimented as one component of 10-11S in all areas and developmental stages. Our findings suggest noncoordinate regulation of brain acetylcholinesterase and pseudocholinesterase, and indicate that the expression of acetylcholinesterase forms within embryonic brain areas depends both on cell type composition and on development.

Acetylcholinesterase↗
PubMed1985

Expression of acetylcholinesterase gene(s) in the human brain: molecular cloning evidence for cross-homologous sequences.

The regulation of acetylcholinesterase (AChE) in the human brain has been approached at the level of the genome. A human DNA fragment of the length of 2 600 nucleotides was isolated from a human genomic library. This DNA fragment, designated Huache 1R, bears sequence homology to a DNA fragment from the vicinity of the Drosophila Ace region, that controls AChE biosynthesis (Soreq et al., 1985). Polyadenylated RNA from human brain was hybridized with Huache 1R DNA, eluted and microinjected into Xenopus oocytes in the absence or presence of 35S-methionine. The hybrid-selected RNA induced the biosynthesis of active AChE in the oocytes. Immunoprecipitation of labeled oocyte proteins with monoclonal antibodies against human AChE (Fambrough et al., 1982) resulted in the selective precipitation of an 85 000 Mr induced protein, with a similar size to that of the subunit of human brain AChE. These findings show that the Huache 1R DNA hybridizes with human brain AChEmRNA. The Huache 1R fragment was employed to select a collection of 12 homologous phage-cloned human genomic DNA fragments with different restriction patterns. A cDNA library in pBR322 plasmids was prepared from polyadenylated RNA isolated from embryonic brain. This library was also screened using labeled Huache 1R DNA as a probe. Forty-two out of 37 000 colonies were found positive. Several of these were selected for further analyses. Hybrid-selection experiments using DNA from two of the positive plasmid clones showed that these cDNAs also hybridize with AChEmRNA from human brain. DNA blot hybridization revealed homologies between these cDNA chains and the original Huache 1 fragment.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1985

Identification of community flour mills as the source of lead poisoning in West Bank Arabs.

Following the discovery of severe lead poisoning in members of several households in a West Bank village, studies were carried out to establish the magnitude of the problem in the community and to identify the source of lead poisoning. Forty-three patients with Centers for Disease Control risk group IV lead poisoning were identified and treated in three villages within a radius of about 10 km of each other. The prevalence of increased lead burden among 563 schoolchildren aged 10 to 18 years was 19% for Centers for Disease Control risk groups I and II and 11% for groups III and IV. A survey of potential sources excluded all items, except for locally ground flour, which was heavily contaminated in all affected households. Examination of community flour mills revealed that, in contrast to unprocessed grain, freshly ground flour contained large amounts of lead originating from lead fillings employed to fasten the housing of the driveshafts to the millstones. Systematic screening of 146 community stone mills in 92 West Bank villages showed significant lead contamination of flour in 33 mills (23%). In all cases, the source of lead contamination was identical. As methods of milling in the area are similar, a prompt investigation of this potential source of lead poisoning in other near-Eastern countries is indicated.

Adolescent↗
PubMed1984

Epidural analgesia for planned vaginal delivery following previous cesarean section.

The effect of lumbar epidural on the course of labor, delivery, and outcome was studied in 115 parturients with a previous cesarean section who were given a trial of vaginal delivery. One hundred three women were multiparous and 12 were grandmultiparous. Uterine contractions and fetal heart rate (FHR) were monitored continuously in all patients. Epidural block was performed using 8 mL of 0.35% bupivacaine without adrenaline. Supplemental doses were administered through an indwelling catheter. At the beginning of the second stage, 10 mL of 0.25% bupivacaine was added in the sitting position. Forty-eight women delivered spontaneously and 54 had an assisted second stage. Thirteen women delivered by a repeat low segmental cesarean section; dehiscence was observed in only one woman. Fetal outcome was satisfactory and similar to that of the authors' general parturient population.

Adult↗
PubMed1983

The peritoneal reaction to the translocated copper intrauterine device in women and female rats.

The observation of a very severe peritoneal reaction to translocated copper-bearing devices in five women necessitated operative removal. Three Copper-T (Ortho Gyne-T, Ortho, Saunderton, High Wycombe, England) and two Copper-7 (Gravigard, Searle, High Wycombe, England) devices were involved. Similarly severe peritoneal reactions were noted in 90% of female rats who had small-sized modified copper devices inserted into their peritoneal cavities. In a control group of rats with the same device but without a copper wire, mild adhesions were observed in the majority (85%), and none had a severe peritoneal reaction. It seems evident that the severe peritoneal reaction is induced by the copper wire in both women and female rats.

Animals↗
PubMed1983

Down's syndrome in twins of unlike sex.

The occurrence of Down's syndrome in both dizygotic twins appears to be very rare. A case of twins of unlike sex is reported, in which chromosomal analysis showed trisomy 21 in both of them, while the parental karyotypes were normal. This is the third reported case of such a constellation, and the second one in which infant and parental chromosomal analysis was done.

Adult↗
PubMed1982

Reported seizures in early childhood: a 14-year follow-up.

A detailed medical history is commonly regarded as a reliable means of classifying unexplained childhood losses of consciousness into diagnostic groups such as febrile seizures, epileptic attacks and breath-holding spells. The authors have tested this assumption by comparing adolescent follow-up status with the initial medical history in 56 individuals who suffered sudden losses of consciousness before age five. Only three of these 56 were epileptic when followed-up in adolescence and only two had received anticonvulsants at any time. The prognosis for 26 individuals with afebrile seizures without evidence of breath-holding syncope was not significantly worse than that for another 16 with febrile seizures. These findings indicate a good prognosis for untreated childhood seizures of a type often classified as epileptic.

Adolescent↗