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Biomedical subjects

J King

Publications and source records attributed to J King.

At least 379 records · Page 21Linked to original sources
PubMed1980

Relation of maternal cigarette smoking, obesity, and energy consumption to infant size.

The dietary energy intakes of 153 public patients (94 smokers and 59 nonsmokers) and 383 Private patients (208 smokers and 175 nonsmokers) were assessed in the last month of pregnancy. Birth weight and crown-heel length of offspring were related to maternal size (weight for height) and smoking habits. Birth weight and length increased significantly with increasing maternal weight for height in the Private group but not in the Public group. In both groups, and in all weight categories, infants of smokers were lighter and shorter than those of nonsmokers. Neither the fetal growth retardation in the smokers nor the fetal growth enhancement in the overweight mothers was explainable on the basis of maternal dietary energy intake. Maternal obesity and cigarette smoking act independently of each other and maternal overweight does not protect the fetus against the growth-retarding of smoking.

Birth Weight↗
PubMed1980

Fetal growth retardation in cigarette-smoking mothers is not due to decreased maternal food intake.

To determine whether the fetal growth-retarding effect of maternal cigarette smoking could be due to a lower dietary intake in smokers than in nonsmokers, the energy and nutrient intake of 302 smoking and 234 nonsmoking women were assessed toward the end of the last trimester of pregnancy. The women were from two socioeconomic groups which differed greatly in age, height, education, family income, racial origin, and pregnancy weight gain. Within each group, smokers had significantly smaller infants, but pregnancy weight gain was not different. Daily dietary intake of the smokers was not less than that of the nonsmokers; in fact, for some nutrients it was significantly greater. Therefore, fetal growth retardation due to smoking is not caused by the mother's diminished intake of food.

Birth Weight↗
PubMed1980

Regulation of coat protein polymerization by the scaffolding protein of bacteriophage P22.

In the morphogenesis of double stranded DNA phages, a precursor protein shell empty of DNA is first assembled and then filled with DNA. The assembly of the correctly dimensioned precursor shell (procapsid) of Salmonella bacteriophage P22 requires the interaction of some 420 coat protein subunits with approximately 200 scaffolding protein subunits to form a double shelled particle with the scaffolding protein on the inside. In the course of DNA packaging, all of the scaffolding protein subunits exit from the procapsid and participate in further rounds of procapsid assembly (King and Casjens. 1974. Nature (Lond.). 251:112-119). To study the mechanism of shell assembly we have purified the coat and scaffolding protein subunits by selective dissociation of isolated procapsids. Both proteins can be obtained as soluble subunits in Tris buffer at near neutral pH. The coat protein sedimented in sucrose gradients as a roughly spherical monomer, while the scaffolding protein sedimented as if it were an elongated monomer. When the two proteins were mixed together in 1.5 M guanidine hydrochloride and dialyzed back to buffer at room temperature, procapsids formed which were very similar in morphology, sedimentation behavior, and protein composition to procapsids formed in vivo. Incubation of either protein alone under the same conditions did not yield any large structures. We interpret these results to mean that the assembly of the shell involves a switching of both proteins from their nonaggregating to their aggregating forms through their mutual interaction. The results are discussed in terms of the general problem of self-regulated assembly and the control of protein polymerization in morphogenesis.

Bacterial Proteins↗
PubMed1980

Scaffolding proteins and the genetic control of virus shell assembly.

Historically a gap has existed between the study of the one-dimensional organization of hereditary information in genes, and of the three-dimensional organization of macromolecules in biological structures. In this article we describe progress in closing this gap through the genetic and biochemical analysis of the assembly of the icosahedral shells of spherical viruses, a class of subcellular structures whose subunit organization is relatively well understood. The genes specifying the proteins required for capsid assembly have been identified for many bacterial viruses. By using mutants defective in these genes, it has been possible to identify intermediates in shell morphogenesis and DNA condensation, and to unravel the different levels of the genetic control of macromolecular assembly processes. In general, a precursor shell or procapsid is first constructed, and the DNA is subsequently coiled within it. The construction of a closed shell poses as difficult a problem for a virus as for an architect. In the well-studied bacteriophage P22 of Salmonella typhimurium, the construction of the procapsid requires the interaction of about 200 molecules of the gene-8 scaffolding protein with 420 molecules of the gene-5 coat protein, forming a double-shelled structure with the scaffolding protein on the inside. Once completed, procapsids undergo substantial alteration in the course of encapsulating the viral DNA. In P22, the initiation of DNA packaging triggers the exit of all of the scaffolding molecules from within the capsid, probably through the coat-protein lattice. These released molecules are re-utilized, interacting with newly synthesized coat subunits to form further procapsids. Thus, the scaffolding protein functions catalytically in capsid assembly. All of the well-studied DNA phages require a scaffolding protein species for procapsid assembly, though their properties vary. Purified coat and scaffolding subunits by themselves show little tendency to polymerize, and are stable as monomers in solution. Upon mixing together under the appropriate conditions, however, the proteins copolymerize into double shells. Their interaction with each other appears to be critical for efficient assembly; this interaction probably occurs on the edges of growing shells, and not among subunits in solution. We have termed this kind of process, which we previously described in T4 tail morphogenesis, self-regulated assembly. The subunits are synthesized in a nonreactive form and are activated, not in solution, but upon incorporation into the growing substrate structure. A number of further transformations of the capsid subunits occur only within the organized structure and not as free subunits. Thus, aspects of the genetic information controlling the assembly process are not fully expressed at the level of the properties of protein subunits, but become manifest only through interactions with other proteins, or at a higher level, after completion of the correct organized structure.

Capsid↗
PubMed1980

Temperature-sensitive mutants blocked in the folding or subunit assembly of the bacteriophage P22 tail-spike protein. I. Fine-structure mapping.

As part of a study of protein folding, we have constructed a fine-structure map of 9 existing and 29 newly isolated UV- and hydroxylamine-induced temperature-sensitive (ts) mutations in gene 9 of Salmonella bacteriophage P22. Gene 9 specifies the polypeptide chain of the multimeric tail spikes, six of which form the cell attachment organelle of the phage. The 38 ts mutants were mapped against deletion lysogens with endpoints in gene 9. They mapped in 10 of the 15 deletion intervals. Two- and three-factor crosses between mutants within each interval indicated that at least 31 ts sites are represented among the 38 mutants. To determine the distribution of ts sites within the physical map, we identified the protein fragments from infection of su- hosts with 10 gene 9 amber mutants. Their molecular weights, ranging from 13,900 to 55,000 daltons, were combined with the genetic data to yield a composite map of gene 9. The 31 ts sites were distributed through most of the gene, but were most densely clustered in the central third.--None of the ts mutant pairs tested exhibited intragenic complementation. Studies of the defective phenotypes of the ts mutants (Goldenberg and King 1981; Smith and King 1981) revealed that most do not affect the thermostability of the mature protein, but instead prevent the folding or subunit assembly of the mutant chains synthesized at restrictive temperature. Thus, many of these ts mutations identify sites in the polypeptide chain that are critical for the folding or maturation of the tail-spike protein.

Chromosome Mapping↗
PubMed1980

A Nitrate Reductase-less Variant Isolated from Suspension Cultures of Datura innoxia (Mill.).

A comparative study has been carried out of the growth of two lines of Datura innoxia (Mill.) cells, designated DI-6 and NR1, their resistance to chlorate, and their ability to assimilate nitrate in sterile culture. The NR1 cell line was isolated from DI-6 cultures by first growing the latter in a nitrate-based medium for 5 days and then transferring the cells to a medium containing 2 grams liter(-1) of casein hydrolysate as the sole N source and 49 millimolar KClO(3) for a 6-week incubation period. Cells which survived the chlorate treatment then were transferred to casein hydrolysate medium and have been cultured in the absence of chlorate for more than 18 months (NR1).DI-6 cells can grow in a nitrate-based medium, whereas NR1 cells can take up nitrate but cannot use it as a N source. The inability of NR1 to assimilate nitrate appears to be due to the lack of an active nitrate reductase in these cells. Through the use of a variety of electron donors and acceptors, the lack of nitrate reductase activity in NR1 cells was shown to be due to the absence of, or a defect in, that component of the enzyme which mediates the reduction of nitrate to nitrite.In other experiments, DI-6 and NR1 were grown on a solid medium containing casein hydrolysate (2 grams liter(-1)) as the sole N source. Under these culture conditions, neither cell line contained an active nitrate reductase. The growth on this medium was compared to that on the same medium containing chlorate at concentrations from 0 to 100 millimolar. DI-6 culture growth was inhibited by 70% at a chlorate concentration of 30 micromolar, whereas growth of NR1 was stimulated by more than 60% on the same medium and by 100% at a chlorate concentration of 30 millimolar. In the presence of 100 millimolar chlorate, the growth of both cell lines was completely inhibited. This clear difference between the response of DI-6 and NR1 cells to chlorate even in the absence of nitrate lends support to the observations by others that chlorate inhibits cells by a mechanism other than, or in addition to, its nitrate reductase-catalyzed conversion to chlorite.Nitrite reductase was induced by nitrate in NR1 cells as well as in DI-6. This observation is a further confirmation of the fact that nitrate, not nitrite, is the true inducer of the nitrate assimilatory pathway in higher plants.

Journal Article↗
PubMed1980

Ophthalmoplegic migraine and aberrant regeneration of the oculomotor nerve.

A patient with ophthalmoplegic migraine developed aberrant regeneration of the oculomotor nerve. This finding supports the view that the oculomotor nerve lesion in ophthalmoplegic migraine is peripheral, but its rarity suggests that the underlying mechanism may be ischaemic rather than compression by an oedematous intracavernous internal carotid artery.

Humans↗
PubMed1979

Drug-induced hyperpyrexia. A case report.

A patient who developed hyperpyrexia and heat stroke after taking overdoses of a monoamine oxidase inhibitor, benzodiazepines and a beta-adrenergic receptor blocking agent is described. The possible mechanisms involved in drug-induced hyperpyrexia are briefly discussed.

Bromazepam↗
PubMed1979

A case of pulsating proptosis.

The long-term follow-up of a case of unilateral pulsating proptosis is reported. The clinical signs in this patient were due to a defect in the bony wall of the orbit which is an unusual manifestation of neurofibromatosis.

Adult↗
PubMed1979

Axillofemoral bypass: intrapleural method.

A new procedure for intrapleural axillary-bilateral femoral bypass is described. This method is proposed as an alternative procedure for bypassing aortoiliac occlusive disease in the high-risk patient.

Aged↗