Nemaline myopathy in a six-month-old Pomeranian dog.

ABSTRACT: Nemaline myopathy - a clinically and genetically complex heterogenous group of disorders - is described uncommonly in humans and rarely in animals, and is characterised by progressive muscle weakness. The diagnosis is confirmed by histological and/or ultrastructural identification of subsarcolemmal, thread-like, rod-shaped structures called nemaline rod bodies within more than 40% of skeletal muscle fibres. These rods contain the Z-line protein, α-actinin, that can be effectively stained in skeletal muscles using Gomori or Masson trichrome and negatively stained with periodic acid-Schiff. Similar rod-like bodies have been found in smaller numbers in dogs with endocrine disorders and occasionally in other conditions in humans. This report is of a six-monthold Pomeranian dog which had progressive exercise intolerance over a two-month period associated with severe disuse muscle atrophy of the thoracic limbs, as well as gradual pelvic limb weakness and regurgitation of food. Baseline diagnostics ruled out endocrinopathies and after histological and ultrastructural evaluation of thoracic limb muscles and nerve biopsies confirmed nemaline myopathy. The clinical course, diagnostic test results, ultrastructure of skeletal muscle and peripheral nerve, gross necropsy findings and histopathology using various stains are described and illustrated.

Ultrasonographic evaluation of fetal development in the rat.

The study objectives were to measure gestational sac (GS) diameter and crown-to-rump (CR) length in conscious pregnant rats and to determine the chronological ultrasonographic appearance of heart beat and fetal organogenesis. The study formed part of a unilateral surgical salpingectomy trial with 16 female Sprague-Dawley rats (Rattus norvegicus). Ten rats were operated on while the other six served as controls. After surgery all were mated at 8-10 weeks of age. Gestational length was taken as 22 days. Rats were manually restrained for abdominal ultrasonography and were scanned daily from day 7 until day 19 or 20 post-mating followed by immediate euthanasia. Measurements' were taken from two GSs per rat. The presence of several early GSs in a row were described as a "string of pearls". As a fetus developed features of organogenesis were recorded. There was no significant difference in GS diameters and CR length between the test and control groups. Mean GS diameters ranged from 2.9 mm (day 7) to 18.1 mm (day 20). A string of pearls was seen on days 8-11. The CR length ranged from 1.6 mm (day 11) to 26.4 mm (day 20). A heart beat was first seen on day 11 and the echogenic vertebral column at day 14-15. From day 16, ribs, feet and the isoechoic lungs and liver were seen. The lungs became hyperechoic to the liver from day 18-19. The tail and mandible were visible on day 18 and the aorta and caudal vena cava were seen on day 19, as well as an occasional bladder. These measurements and staged in utero ultrasonographic appearance of various organ and skeletal structures will assist in a reasonably accurate prediction of the day of impending parturition by laboratory personnel and researchers.

Biofilm form and function: carbon availability affects biofilm architecture, metabolic activity and planktonic cell yield.

AIMS: To investigate carbon transformation by biofilms and changes in biofilm architecture, metabolic activity and planktonic cell yield in response to fluctuating carbon availability. METHODS AND RESULTS: Pseudomonas sp. biofilms were cultured under alternating carbon-replete and carbon-limited conditions. A shift to medium without added carbon led to a 90% decrease in biofilm respiration rate and a 40% reduction in planktonic cell yield within 1 h. Attached cell division and progeny release were shown to contribute to planktonic cell numbers during carbon limitation. Development of a significantly enlarged biofilm surface area during carbon limitation facilitated a rapid increase in whole-biofilm metabolic activity, cell yield and biomass upon the re-introduction of carbon after 8 days of limitation. The cumulative number of planktonic cells (>10(10) CFU) released from the biofilm during the cultivation period contained only 1·0% of the total carbon available to the biofilm, with 6·5% of the carbon retained in the biofilm and 54% mineralized to CO(2) . CONCLUSIONS: Biofilm-derived planktonic cell yield is a proliferation mechanism. The rapid response of biofilms to environmental perturbations facilitates the optimal utilization of resources to promote both proliferation and survival. Biofilms function as efficient catalysts for environmental carbon transformation and mineralization. SIGNIFICANCE AND IMPACT OF THE STUDY: A greater understanding of the relationship between biofilm form and function can inform strategies intended to control and/or promote biofilm formation.