A study of the prevalence of rotavirus infection in children with gastroenteritis admitted to an infectious diseases hospital.

In a 12 month survey of infants and children with gastroenteritis admitted to Fairfield Hospital, Melbourne, rotavirus was found in approximately 42% of patients. This virus was detected more often during the winter months, particularly in children aged between 12 months and 3 years. Detection of rotavirus by electron microscopy was found to be more sensitive than by counterimmunoelectrophoresis. Routine bacterial and viral studies revealed that bacterial pathogens and common enteric viruses were associated with relatively few cases of gastroenteritis. There is little doubt that rotavirus is the most important aetiological agent of acute gastroenteritis in yvirus is the most important aetiological agent of acute gastroenteritis in young children in Melbourne.     

Changes in triceps surae muscle architecture with sarcopenia

AIM: To investigate whether sarcopenia was evenly distributed among the three components of the triceps surae (TS) muscle group. METHODS: Muscle volume (VOL), fibre fascicle length (Lf), pennation angle (theta) and physiological cross-sectional area (PCSA = VOL/Lf) were measured in vivo for the lateral (GL) and medial (GM) heads of the gastrocnemius muscles and for the soleus muscle (SOL), in 15 young males (YM, aged 25.3 +/- 4.5 years) and 12 elderly males (EM aged 73.8 +/- 4.4 years). RESULTS: In the EM, VOL of all three muscles was significantly smaller than in the YM; differences were: 27% for the GL (P < 0.01), 29% for the GM (P < 0.01) and 17% for the SOL (P < 0.05). In total, TS VOL was 22% smaller in EM than in YM (P < 0.01). In the EM, values of theta were significantly smaller than in the YM; by 15-18% for the GL, GM and SOL (P < 0.05). In the EM, Lf of the GM was 16% smaller than in the YM (P < 0.01); no significant differences were found in the other muscles. PCSA of the GL and GM were both found to be smaller in EM by 19% (P < 0.01) and 14.5% (P < 0.05), respectively. No difference was observed in the SOL PCSA between YM and EM. Interestingly, probably because of the prevalent contribution of the SOL to PCSA distribution of each muscle to the TS PCSA, the relative TS PCSA was not different between YM and EM. Furthermore, the Lf/muscle length ratio did not differ between YM and EM. CONCLUSION: The present study shows that the relative PCSA composition of the TS is maintained with ageing and that the PCSA is scaled down harmonically with the decrease in muscle volume and fascicle length. Such observation suggests that the relative contribution of the components of the TS muscle to the total force developed by this muscle group is maintained with ageing.     

Unit activity in posterior association cortex of cat.

1. "Association" neurons in the posterior middle suprasylvian gyrus of cat were found to be predominantly polysensory, with 82% of the units in the chloralose-anesthetized preparation responding to auditory, visual, and somatic stimuli. There was no evidence of response differentiation associated with cortical depth distribution. Most units responded with a short-latency response (median 35-60 ms) to all stimulus modalities, with the response to visual stimulation occurring at the shortest latency. Among polysensory cells, almost half responded with equal probability to auditory, visual, and somatic stimulation. The visual stimulus was the most potent for those cells responding with a higher probability to a single modality. Varying degrees of response complexity were noted in some cells in terms of changes in responsivity over time, discharge to stimulus offset, and inhibition of spontaneous activity. The unitary discharge was seen to occur on the negative peak and slope of the locally recorded evoked potential. When only the larger amplitude spikes were analyzed, most of the unitary activity occurred on the negative peak of the evoked potential. Almost half of trimodally responsive cells displayed similar phase relationships between unitary activity and evoked potentials for all three modalities. The absolute refractory period for most cells was from 200 to 300 ms, with relative refractory periods extending up to 30 s...     

Muscle strength, volume and activation following 12-month resistance training in 70-year-old males

In elderly males muscle plantar flexor maximal voluntary contraction (MVC) torque normalised to muscle volume (MVC/VOL) is reduced compared to young males as a result of incomplete muscle activation in the elderly. The aim of the present study was to determine the influence of a 12-month resistance training programme on muscle volume, strength, MVC/VOL, agonist activation and antagonist coactivation of the plantarfexors in elderly males. Thirteen elderly males aged 70 years and over (range 70–82 years), completed a 12-month whole body resistance-training programme (TRN), training three times a week. Another eight males (range 18–30 years), who maintained their habitual physical activity for the same 12-month period as the TRN group acted as controls (CTRL). Isometric plantarflexor maximal voluntary contraction (MVC) torque increased in the TRN group by 20% (P<0.01), from 113.1±22.0 Nm to 141.5±19.2 Nm. Triceps surae volume (TS VOL) assessed using MRI, increased by 12%, from 796.3±78.9 cm³ to 916.8±144.4 cm³ . PF activation, measured using supramaximal double twitch interpolation, increased from 83.6±11.0% pre training, to 92.1±7.6% post training (P<0.05). Dorsiflexion MVC and antagonist coactivation (assessed using surface electromyography) did not change with training. Plantarflexor MVC torque normalized for triceps surae muscle volume (MVC/VOL) was 142.6±32.4 kN m^–2 before training and 157.0± 27.9 kN m^–2 after training (a non-significant increase of 8%). No significant change in any measurement was observed in the CTRL group. This study has shown that the gain in muscle strength in response to long-term (12-month) training in older men is mostly accounted for by an increased muscle volume and activation.     

Growth in North American white children with neurofibromatosis 1 (NF1)

OBJECTIVE—To analyse the distributions of and generate growth charts for stature and occipitofrontal circumference (OFC) in neurofibromatosis 1 (NF1) patients.
DESIGN—Cross sectional database survey.
SETTING—The National Neurofibromatosis Foundation International Database (NFDB) includes clinical information on NF1 patients from 14 participating centres in North America.
SUBJECTS—A total of 569 white, North American, NF1 patients, 55% female and 45% male.
MAIN OUTCOME MEASURES—Stature and OFC measurements of NF1 patients were compared to age and sex matched population norms using z score standardisation and centile curves.
RESULTS—The distributions of stature and OFC are shifted and unimodal among NF1 patients; 13% of patients have short stature (2 standard deviations below the population mean) and 24% have macrocephaly (OFC 2 standard deviations above the population mean).
CONCLUSIONS—Alterations of stature and OFC are not limited to NF1 patients with frank short stature or macrocephaly.


Keywords: neurofibromatosis 1; stature; occipitofrontal circumference; macrocephaly     

Homozygosity mapping of achromatopsia to chromosome 2 using DNA pooling

Achromatopsia is an autosomal recessive disease of the retina, characterized clinically by an inability to distinguish colors, impaired visual acuity, nystagmus and photophobia. A genome-wide search for linkage was performed using an inbred Jewish kindred from Iran. To facilitate the genome-wide search, we utilized a DNA pooling strategy which takes advantage of the likelihood that the disease in this inbred kindred is inherited by all affected individuals from a common founder. Equal molar amounts of DNA from all affected individuals were pooled and used as the PCR template for short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected members of the kindred was used as a control. A reduction in the number of alleles in the affected versus control pool was observed at several loci. Upon genotyping of individual family members, significant linkage was established between the disease phenotype and markers localized on chromosome 2. The highest LOD score observed was 5.4 (theta = 0). When four additional small unrelated families were genotyped, the combined peak LOD score was 8.2. Analysis of recombinant chromosomes revealed that the disease gene lies within a 30 cM interval which spans the centromere. Additional fine-mapping studies identified a region of homozygosity in all affected individuals, narrowing the region to 14 cM. A candidate gene for achromatopsia was excluded from this disease interval by radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an essential first step in the identification of the disease-causing gene.      

Early restriction of tactile stimulation and visual functioning in the kitten

Twelve kittens with vibrissae clipped on the 1st day of life were compared to matched controls for the development of a preferential behavior in a visual cliff situation in an effort to examine the developmental relationship between sense systems. The kittens with reduced tactile input (vibrissae-clipped) were found to discriminate between the “shallow” and “Sdeep” sides of the visual cliff at younger ages and with greater consistency than controls. The results for which there are alternative explanations available support the hypothesis that reduction of input in one modality reduces competition between sense systems, thereby resulting in the precocial use of another sense system.