Tentoxin sensitivity of chloroplasts determined by codon 83 of beta subunit of proton-ATPase

Tentoxin is a naturally occurring phytotoxic peptide that causes seedling chlorosis and arrests growth in sensitive plants and algae. In vitro, it inhibits activity of the beta subunit of the plastid proton-adenosine triphosphatase (ATPase) from sensitive species. Plastid atpB genes from six closely related, tentoxin-sensitive or -resistant Nicotiana species differ at codon 83, according to their response to the toxin: glutamate correlated with resistance and aspartate correlated with sensitivity. The genetic relevance of this site was confirmed in Chlamydomonas reinhardtii by chloroplast transformation. The alga, normally tentoxin-resistant, was rendered tentoxin-sensitive by mutagenesis of its plastid atpB gene at codon 83. Codon 83 may represent a critical site on the beta subunit that does not compete with nucleotide binding or other catalytic activities.

Reactivation of the chloroplast CF1-ATPase beta subunit by trace amounts of the CF1 alpha subunit suggests a chaperonin-like activity for CF1 alpha

Incubation of tobacco and lettuce thylakoids with 2 M LiCl in the presence of MgATP removes the beta subunit from their CF1-ATPase (CF1 beta) together with varying amounts of the CF1 alpha subunit (CF1 alpha). These 2 M LiCl extracts, as with the one obtained from spinach thylakoids (Avital, S., and Gromet-Elhanan, Z. (1991) J. Biol. Chem. 266, 7067-7072), could form active hybrid ATPases when reconstituted into inactive beta-less Rhodospirillum rubrum chromatophores. Pure CF1 beta fractions that have been isolated from these extracts could not form such active hybrids by themselves, but could do so when supplemented with trace amounts (less than 5%) of CF1 alpha. A mitochondrial F1-ATPase alpha subunit was recently reported to be a heat-shock protein, having two amino acid sequences that show a highly conserved identity with sequences found in molecular chaperones (Luis, A. M., Alconada, A., and Cuezva, J. M. (1990) J. Biol. Chem. 265, 7713-7716). These sequences are also conserved in CF1 alpha isolated from various plants, but not in F1 beta subunits. The above described reactivation of CF1 beta by trace amounts of CF1 alpha could thus be due to a chaperonin-like function of CF1 alpha, which involves the correct, active folding of isolated pure CF1 beta.

Direct selection for paternal inheritance of chloroplasts in sexual progeny of Nicotiana

The response of Nicotiana tabacum to tentoxin (chlorosis) is inherited with chloroplasts. N. tabacum var. Xanthi, a tentoxin-resistant line, was used to pollinate tentoxin-sensitive N. tabacum line 92, an alloplasmic male-sterile line containing N. undulata plastids. The seeds were mutagenized with nitrosomethylurea and germinated in the presence of tentoxin. Two percent of the seedlings had green sectors in their first true leaves. These plants were grown to maturity under non-selective conditions. Homogeneous tentoxin-resistant lines were obtained in the third generation. DNA analysis indicated, however, that selection for paternal plastids, rather than mutagenesis of maternal ones, had occurred in the tentoxin-resistant progeny. Mitochondria, which were not under selection pressure, were inherited maternally as expected. Inheritance of tentoxin-resistant paternal plastids did not require seed mutagenesis. Normally germinated seedlings that were kept under tentoxin selection consistently produced a low level of resistant green sectors in their first true leaves. Thus, normal, low-frequency transmission of paternal plastids in N. tabacum can be directly revealed by using tentoxin.

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.

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.

Nonsurgical management of uncomplicated intrahepatic hematomas following blunt abdominal trauma

A 45-year-old man who sustained blunt abdominal trauma was found to have a huge intrahepatic hematoma. Although early abdominal exploration is usually recommended for suspected hepatic injury, this case was managed nonsurgically by careful observation, with gradual resolution of the hematoma as seen on serial liver scans.

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.

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.

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.

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.

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.

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.

Syndrome of inappropriate antidiuretic hormone secretion in newborn infants with respiratory problems

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) has not often been described in newborn infants. Of 61 infants with respiratory problems who were admitted to our neonatal intensive care unit over a six-month period from July 1978, three had SIADH, diagnosed on the basis of hyponatremia, weight gain and the excretion of highly concentrated urine. In one infant the onset of marked hyponatremia was very rapid and resulted in deep coma. The occurrence of this syndrome in 5% of infants under intensive care for neonatal respiratory problems makes it essential to monitor these infants closely for deviations in fluid and electrolyte balance.

Antibody pattern to human cytomegalovirus in patients with adenocarcinoma of the colon

The role of human cytomegalovirus (CMV) was examined according to serological patterns in 37 patients with adenocarcinoma of the colon (ACC). The sera were examined for the presence of IgG antibodies by the immunoperoxidase antibody to membrane antigens (IPAMA) method and by the complement-fixation (CF) test. Antibody determinations were also performed by the IPAMA method for three other members of the herpesvirus group: Epstein-Barr virus (EBV), herpes simplex virus (HSV) and varicella-zoster virus (VZV). Comparison groups included normal subjects, ACC patients treated with chemotherapy, and patients operated on for benign diseases. No significant difference was found in the geometric mean titers (GMTs) for CMV and the other herpesviruses in the sera of nontreated ACC patients when compared with the control groups. However, a significantly elevated antibody titer to CMV was found in chemotherapy-treated ACC patients by both the IPAMA and CF methods. In this group, elevated titers were found by the IPAMA method for EBV and HSV, but not for VZV. The significance of serological studies in elucidating the role of CMV in ACC patients is discussed.

Ovarian pregnancy and IUD

Two cases of ovarian pregnancy associated with an IUD in situ are described. One of the cases documents the first reported case of ovarian pregnancy coexisting with a Copper-T device; thus the range of types of IUDs combined with ovarian pregnancy is further extended. The consciousness of the physician of the coexistence, in combination with the wide use of updated diagnostic means, especially estimations of low values of HCG and laparoscopy, should ensure early diagnosis of ectopic pregnancies, including ovarian ones.

Thymic hormonal activity on human peripheral blood lymphocytes, in vitro. I. Reciprocal effect on T and B rosette formation

One hour incubation with the thymic extract TP-1 induced reciprocal effect on B and T rosette formation in lymphocytes of human peripheral blood. The percentage of mouse erythrocyte rosette-forming cells among lymphocytes of chronic lymphatic leukaemia was decreased by TP-1 from 54.5% to 27.1% (P < 0.001). No such effect was observed in healthy adult or cord blood lymphocytes. On the other hand, the percentage of sheep erythrocyte rosette forming cells increased significantly after TP-1 treatment, but only under conditions of active rosette formation and not in the total rosette assay. This increase was highly significant in three conditions with relative deficiency of cell-mediated immunity: newborns (17.1 to 28.3%), cancer patients (24.5 to 31.7%) and patients with lepromatous leprosy (19.8 to 31.8%). Only a small increase was noticed in healthy adults. A similarly prepared spleen extract was not active in either B or T rosette assays.