Outcome of acute lower respiratory tract infection in infants: preliminary report of seven-year follow-up study.

Seven years after admission to hospital for acute lower respiratory tract infection in infancy 200 children and their matched controls were assessed for respiratory state and epidemiological characteristics. The index group comprised 100 cases where respiratory syncytial virus infection had been responsible for the index illness (group 1) and 100 cases in whom this organism had not been found (group 2). There were no differences between index and control groups in birth weight or gestational age but fewer index cases were breast fed. Social indices such as class distribution and family size were more favourable in controls, though housing standards and maternal smoking habits were similar in the two groups. The prevalence of subsequent respiratory symptoms--cough, wheeze, nasal discharge, and hearing difficulties--was greater in index cases as was absence from school and family doctor consultation for respiratory illness. Bronchitis and asthma were significantly more common in the index group. Impaired ventilatory function and bronchial hyperreactivity were found in index cases when compared with controls. No differences in clinical characteristics and outcome were found in the two groups of index cases. The question whether lung "damage" during lower respiratory tract infection predisposes to subsequent respiratory problems or whether certain infants are more vulnerable than others to respiratory illnesses (including lower respiratory tract infection) from the onset is unanswered.     

Treatment of spinal osteoporosis in postmenopausal women.

Ninety-five postmenopausal women with unequivocably wedged or compressed vertebrae in whom the recognised causes of secondary osteoporosis had been excluded were studied, 41 having no treatment and the rest one or more of six different treatments. The treatment regimens comprised calcium supplements, vitamin D, calcium and vitamin D, ethinyloestradiol or--where oestrogens were contraindicated--norethisterone, 1 alpha-hydroxycholecalciferol (1 alpha-OHD3), or hormones with 1 alpha-OHD3. The seven groups were reasonably comparable in most respects except that the hormone-treated patients were younger and had a higher initial cortical area ratio than the others, and the calcium- and hormone-treated groups had the best initial radio-calcium absorption. The untreated osteoporotic patients lost cortical bone more rapidly than do normal postmenopausal women. Three treatments (calcium, hormones, and 1 alpha OHD3 plus hormones) appear to be useful in modifying the disease, and two treatments (vitamin D and 1 alpha-OHD3) useless or even harmful. Vitamin D and 1 alpha-OHD3 are more safely used in conjunction with oestrogens, which protect bone against resorption, than on their own.     

Event recording in a clinical trial of a new medicine.

In a double-blind trial of the effect of zimelidine on weight and appetite 24 obese patients were allocated at random to receive either zimelidine or placebo for eight weeks followed by the alternative treatment for eight weeks. Possible adverse effects were elicited by asking patients at weekly intervals whether they had experienced any symptoms or ailments and recording all such "events" on a special form. A conventional checklist of symptoms was also used. Among 19 patients who completed the trial the two methods of recording yielded similar patterns of events. Of symptoms not on the checklist, insomnia was more common during treatment with zimelidine. Event recording was found to be a practicable and convenient method of detecting possible adverse effects.     

Differential mitotic rates and patterns of growth in compartments in the Drosophila wing

In the wing disks of Drosophila slowly dividing cells of Minute mutations are progressively eliminated from Minute/Minute⁺ mosaic compartments by a process known as cell competition. From a study of two different Minutes we show here that the intensity of competition is greater in the more extreme Minute with the slowest rate of cell division. The way in which the more rapidly growing Minute⁺ clones grow and overcome the surrounding Minute cells is described and cell competition is shown to be a result of local interactions between slow- and faster-growing cells.     

Effects of condensed phosphates on plant growth and phosphorus uptake

Summary Four condensed phosphates with large and small molecules, including ring and chain structures, were equivalent to orthophosphate in terms of phosphorus uptake and the dry matter yield of ryegrass grown in two soils in pots. This equivalence was maintained at each of 6 cuts during two seasons.Increasing N rate greatly increased uptake of applied phosphorus but there was no differential effect with different sources of phosphorus, nor was there any interaction between source and application rate.Phosphorus was not leached at any time, indicating that the phosphates were rapidly adsorbed by the soils.Fairly rapid hydrolysis of all the condensed phosphates occurred in a soil of neutral pH but a slower hydrolysis seemed to occur in an acid soil.There was a good correlation between the phosphorus uptake by ryegrass and the additional orthophosphate released by an acid hydrolysis of soil extracts.     

Production of rats in synchronised batches.

Successful synchronisation of copulations and births for the 1st parity permit continued synchrony of parturitions in subsequent parities. Foetal implantation after post-partum copulation was delayed by multiples of the oestrous cycle; both season and number of sucking neonates influenced the time of implantation. Post-weaning matings gave a high conception rate with a parturition spread of 36 hours for 94% of the original group.     

Effects of cycloheximide on chromatin biosynthesis.

In the presence of sufficient cycloheximide, puromycin or NaCl to quantitatively inhibit protein synthesis in HeLa cells, thymidine incorporation continues at 20% of control rates for 60 to 90 minutes, after which incorporation gradually ceases. Both DNA and protein synthesis revert to control rates in about five minutes after removal of cycloheximide.DNA synthesis in the presence of cycloheximide appears to be a continuation of the replicative process by several criteria. The persistent DNA synthesis in the presence of cycloheximide is abolished by hydroxyurea, which does not inhibit repair synthesis, while ethidium bromide, an inhibitor of mitochondrial DNA synthesis, is without effect. Nuclear DNA is not nicked during incubation in cycloheximide. Low molecular weight Okazaki fragments (4 to 5 S) are both synthesized and processed to high molecular weight DNA in cells treated with cycloheximide. Replication forks, identified in alkaline CsCl gradients by incorporation of bromodeoxyuridine as a density marker just before the addition of cycloheximide, are selectively labeled with radioactive thymidine during DNA synthesis.In the presence of cycloheximide the maturation of DNA intermediates into high molecular weight DNA is defective. All size classes of DNA fragments, normally present during progression of low to high molecular weight DNA, are demonstrable in cells preincubated in cycloheximide for prolonged periods. However, 21 S fragments, intermediate in size between Okazaki pieces and mature, high molecular weight DNA, accumulate in cells treated with cycloheximide, demonstrating a defect in maturation of the 21 S intermediates into high molecular weight DNA. After removal of the cycloheximide, the 21 S DNA fragments are processed to high molecular weight DNA at a significantly impaired rate, requiring about three hours for completion of chain growth as compared to 40 to 60 minutes in controls. The slowed growth of DNA fragments synthesized in the presence of cycloheximide following drug removal is not due to persisting effects of cyeloheximide since DNA synthesis immediately following removal of the drug has chain growth rates similar to that of controls.Pools of chromatin proteins exist in HeLa cells, as demonstrated by a brief, labeled amino acid pulse followed by a chase with cycloheximide. The specific activity of chromatin proteins increases significantly during 60 minutes of cycloheximide inhibition. Histone f2a1 accumulates preferentially during this chase period, suggesting that a supply of this highly conserved histone might be requisite to continued replication.Comparison of chromatin synthesized during cycloheximide treatment with pulse-labeled control chromatin has provided insight into the mechanism of assembly of proteins and DNA into the nucleoprotein complex. The DNA of ch-chromatin² is more susceptible to nuclease digestion than control chromatin, suggesting that it is deficient in protein content. Upon reversal of cycloheximide inhibition, the recovery of nuclease digestibility of ch-chromatin to control values takes two to three hours, a time similar to that required for conversion of the corresponding 21 S chDNA fragments to high molecular weight DNA. Briefly pulse-labeled (30 to 60 s) DNA in control chromatin also has an enhanced susceptibility to nuclease digestion of the same degree as found in ch-ehromatin. The time of recovery of increased nuclease susceptibility of newly made chromatin DNA (via protein addition) to control levels is about 10 to 15 minutes and corresponds to the time required for synthesis of replicon-sized units of DNA.In addition to being nuclease-sensitive, both cycloheximide and newly synthesized (30 to 60 s) chromatin have lighter buoyant densities in CsCl gradients than bulk chromatin. This property exists for only one to two minutes in controls and is probably due to structural properties distinct from those rendering nuclease sensitivity.Limit digests of chromatin by micrococcal nuclease yield a characteristic pattern of polynucleotides when resolved in polyacrylamide gels. The radioactivity profiles of limit digest polynucleotides from control and ch-chromatin are identical, indicating that pre-existing chromatin proteins remain in place on newly replicated DNA in the same fashion as in mature chromatin.