Redistribution of carbonic anhydrase VI expression from ducts to acini during development of ovine parotid and submandibular glands

 Carbonic anhydrase VI (CA VI) is a secreted enzyme produced predominantly by serous acinar cells of submandibular and parotid glands. We have investigated the developmental pattern of CA VI production by these glands in the sheep, from fetal life to adulthood, using immunohistochemistry. Also, a specific radioimmunoassay for CA VI was used to measure changes in enzyme expression in the parotid gland postnatally. CA VI is detectable by immunohistochemistry in parotid excretory ducts from 106 days gestation (term is 145 days), in striated ducts from 138 days and in acinar cells from 1 day postnatal. The duct cell content of CA VI declined as the acinar cell population increased, a feature also of CA VI immunoreactivity in the submandibular gland. Production of CA VI by submandibular duct cells was detectable initially at 125 days gestation, and acinar production was not seen before 29 days post-natal. Apart from the differing ontogeny of CA VI production in ducts and acini of parotid and submandibular glands, there was a parallel pattern of CA VI expression during the development of these major salivary glands.With the development of the acinar tissues in the postnatal lamb, there was a dramatic increase (about 600-fold) in the level of expression of CA VI in the parotid gland between days 7 and 59 as measured by radioimmunoassay. Accepted: 19 December 1996     

Expression of Bcl-2 protein in the epiphyseal plate cartilage and trabecular bone of growing rats

 The protooncogene protein, Bcl-2, protects cells from apoptosis and ensures their survival in vitro by inhibiting the action of the apoptosis-inducer, Bax. Its expression in proliferative and long-lived cells in vivo also indicates that it protects against cell death. The chondrocytes of the epiphyseal plate cartilage undergo a series of maturation steps and deposit mineral in the cartilage matrix before dying. The possibility that Bcl-2 helps protect chondrocytes until mineral deposition is completed was investigated by determining the distribution of Bcl-2 immunoreactivity in the epiphyseal plate cartilage of growing rats and its subcellular localization, using a specific antibody. The involvement of Bax in the triggering of chondrocyte death was checked by immunocytochemistry. Bcl-2 expression in the osteoblasts and the final result of their evolution, the osteocytes, was also examined in trabecular bone. Bcl-2 immunoreactivity was non-uniformly distributed throughout the epiphyseal cartilage. It was maximal in proliferative chondrocytes, decreased in mature chondrocytes, and low in hypertrophic chondrocytes, whereas there was Bax immunoreactivity in all chondrocytes examined. Immunolabeling was intense in osteoblasts but considerably lower in fully differentiated osteocytes. Bcl-2 immunoreactivity was mainly in the cytoplasm of chondrocytes, osteoblasts, and early osteocytes; the nuclei appeared clear. The subcellular distribution of Bcl-2 immunolabeling in chondrocytes, revealed by gold particles in the electron microscope, showed that gold particles were frequently concentrated in the mitochondria in all the cartilage zones and lay mainly within the organelles, not at their periphery. The endoplasmic reticulum contained moderate immunoreactivity and there were few gold particles in the cytoplasm and nuclei. The number of gold particles decreased in all the subcellular compartments from proliferative to hypertrophic chondrocytes. In contrast, Bax immunoreactivity changed little during chondrocyte terminal evolution, and its subcellular distribution mirrored that of Bcl-2. These immunocytochemical data indicate that Bcl-2 helps maintain chondrocytes and osteoblasts until their terminal maturation. Accepted: 19 February 1997     

Ecological correlates of hind-limb length in the Carnivora

What determines the lengths and proportions of mammalian limbs? While the answer to this question is still largely unknown, a number of workers have recently begun analysing the selection of morphology in a rigorous framework, searching for quantitative links between structure, performance, and their ecological and behavioural context. The present study investigates a variety of ecological and behavioural variables to determine whether or not they are correlated with hind-limb length in the Carnivora. Data were analysed by using phylogenetically independent contrasts and phylogenetic analysis of covariance. We found that traditional perceptions of limb length are often inaccurate; some species widely regarded as relatively long-legged actually have limb lengths near those expected for their body size. Interestingly, relative hind-limb length is not a significant predictor of distance moved daily, home-range area, or prey size. Phylogenetic ANCOVA results, however, indicate a relationship between prey-capture behaviour and relative hind-limb length. These findings suggest that the evolution of carnivoran limb length has been most influenced by selection for prey-capture behaviour. These results, coupled with those of other studies, can be used to suggest which performance variables could most fruitfully be studied in the laboratory to understand the selection of the structure of the mammalian limb. We suggest that relevant performance variables might be: maximum jump height and/or length, the ability to generate outforces, and levels of stress tolerance in limb bones during prey pursuit/capture.     

Prospective study of effect of switching from cigarettes to pipes or cigars on mortality from three smoking related diseases.

OBJECTIVE: To estimate the extent to which cigarette smokers who switch to cigars or pipes alter their risk of dying of three-smoking related diseases-lung cancer, ischaemic heart disease, and chronic obstructive lung disease. DESIGN: A prospective study of 21520 men aged 35-64 years when recruited in 1975-82 with detailed history of smoking and measurement of carboxyhaemoglobin. MAIN OUTCOME MEASURES: Notification of deaths (to 1993) classified by cause. RESULTS: Pipe and cigar smokers who had switched from cigarettes over 20 years before entry to the study smoked less tobacco than cigarette smokers (8.1 g/day v 20 g/day), but they had the same consumption as pipe and cigar smokers who had never smoked cigarettes (8.1 g) and had higher carboxyhaemoglobin saturations (1.2% v 1.0%, P < 0.001), indicating that they inhaled tobacco smoke to a greater extent. They had a 51% higher risk of dying of the three smoking related diseases than pipe or cigar smokers who had never smoked cigarettes (relative risk 1.51; 95% confidence interval 0.96 to 2.38), a 68% higher risk than lifelong non-smokers (1.68; 1.16 to 2.45), a 57% higher risk than former cigarette smokers who gave up smoking over 20 years before entry (1.57; 1.04 to 2.38), and a 46% lower risk than continuing cigarette smokers (0.54; 0.38 to 0.77). CONCLUSION: Cigarette smokers who have difficulty in giving up smoking altogether are better off changing to cigars or pipes than continuing to smoke cigarettes. Much of the effect is due to the reduction in the quantity of tobacco smoked, and some is due to inhaling less. Men who switch do not, however, achieve the lower risk of pipe and cigar smokers who have never smoked cigarettes. All pipe and cigar smokers have a greater risk of lung cancer than lifelong non-smokers or former smokers.     

Almitrine and doxapram decrease fatigue and increase subsequent recovery in isolated rat diaphragm

McGuire, Michelle, Michael F. Carey, and John J. O'Connor.Almitrine and doxapram decrease fatigue and increase subsequent recovery in isolated rat diaphragm. J. Appl.Physiol. 83(1): 52-58, 1997.The effects ofalmitrine bimesylate and doxapram HCl on isometric force produced by invitro rat diaphragm were studied during direct muscle activation at37°C. Doxapram and almitrine ameliorate respiratory failureclinically by indirectly increasing phrenic nerve activity. This studywas carried out to investigate possible direct actions of these agentson the diaphragm before and after fatigue of the fibers. Two age groupsof animals were chosen [6-14 wk (group1) and 50-55 wk (group2)] because it is known that increasing agedecreases a muscle fiber's resistance to fatigue. Muscle strips wereisolated from both group 1 and group 2 and directly stimulated (2-mspulse duration, 5-15 V) to produce twitch tensions of 1.3 and 2.1 N/cm², respectively. At lowconcentrations, doxapram (20 µg/ml) and almitrine (12 µg/ml)had no effect on twitch contraction or 100-Hz tetanic tension. However,40 µg/ml doxapram and 30 µg/ml almitrine increased twitch tensionby 9.0 ± 1.4 and 11.6 ± 1.9%, respectively, in animals ofgroup 2 (n = 5). A fatigue protocol consistingof low-frequency stimulation (30-Hz trains, 250-ms duration every 2 sfor 5 min) caused a reduction of twitch tension in animals ofgroup 1 (48 ± 4% ofcontrol) and group 2 (28 ± 4% ofcontrol). At 90 min postfatigue, the twitch tension recovered to 72 ± 3 and 42 ± 2% of control values ingroup 1 and group2, respectively. In the presence of doxapram (20 µg/ml), there was a significant increase in the recovery of twitchtension at 90 min in group 1 andgroup 2 (84.5 ± 3.2 and 80.1 ± 2.8%, respectively) compared with controls at 90 min postfatigue. Inthe presence of almitrine (12 µg/ml), there was a full recovery fromfatigue in group 1 animals (100% ofcontrol) and a recovery to 95.6 ± 2.1% of control ingroup 2 animals at 90 min. Theseresults demonstrate a significant improvement in the rapidity andmagnitude of recovery from fatigue in the rat diaphragm muscle in thepresence of both doxapram and, especially, almitrine. These effects maybe due to changes in intracellular calcium, ADP/ATP ratios, or oxygenfree radical scavenging.

     

Tyrosine hydroxylase in the cerebral ganglia of the American cockroach (Periplaneta americana L.): an immunohistochemical study

We have investigated the distribution of tyrosine-hydroxylase-like immunoreactivity in the cerebral ganglia of the American cockroach, Periplaneta americana. Groups of tyrosine-hydroxylase-immunoreactive cell bodies occur in various parts of the three regions of the cerebral ganglia. In the protocerebrum, single large neurons or small groups of neurons are located in the lateral neuropil, adjacent to the calyces, and in the dorsal portion of the pars intercerebralis. Small scattered cell bodies are found in the outer layers of the optic lobe, and clusters of larger cell bodies can be found in the deutocerebrum, medial and lateral to the antennal glomeruli. Thick bundles of tyrosine-hydroxylase-positive nerve fibers traverse the neuropil in the proto- and deutocerebrum and innervate the glomerular and the nonglomerular neuropil with fine varicose terminals. Dense terminal patterns are present in the medulla and lobula of the optic lobe, the pars intercerebralis, the medial tritocerebrum, and the area surrounding the antennal glomeruli, the central body and the mushroom bodies. The pattern of tyrosine-hydroxylase-like immunoreactivity is similar to that previously described for catecholaminergic neurons, but it is distinctly different from the distribution of histaminergic and serotonergic neurons.     

Seasonal and area-related variations in the diet of otters Lutra lutra on Mull

The diet of otters Lurra lutrn living in a sea loch on the Isle of Mull was described by means of spraint analysis. Seasonal and spatial differences in the spraint composition were explored in the context of fluctuations in prey availability, as revealed by trapping. Butterfish Pholis gunnellus and the cottids Myoxocephalus scorpius and Taurulus bubalis were the most commonly occurring prey in spraints. In the winter, the proportion of rocklings ( Ciliata spp. and Gaidropsarus spp.) and non-rockling gadoids (Gadidae) in the diet increased. Their relatively large size makes these latter species an important constituent of the winter diet. Seasonal and spatial variation in fish consumption largely reflected fluctuations in availability. The mean size of principal prey fishes in spraints was similar to that observed in the traps. These observations suggest that otters were not strongly selective with regard to fish species and size. Shore crabs, in contrast, were not taken in proportion to availability. The findings are discussed in the light of other studies of the diet of coastal otters. It is suggested that the lack of selectivity demonstrated in this study, compared with previous studies, may be explained by area-related variations in prey availability.     

The complete amino acid sequence of the major alpha subunit of the lectin from the seeds of Dioclea grandiflora (Mart)

The complete amino acid sequence of the major alpha subunit of the lectin from seeds of Dioclea grandiflora was determined. The sequence was deduced from analysis of peptides derived from the native alpha subunit by digestion with trypsin, chymotrypsin, the Staphylococcus aureus V8 protease, and pepsin; and from larger peptides produced by digestion of the citraconylated protein with trypsin. The alpha subunit consists of a single polypeptide chain of 237 amino acids which differs from the sequence of concanavalin in 53 positions. Significant levels of heterogeneity were observed in five positions in the sequence.     

Reciprocal translocation and the Philadelphia chromosome

Summary We examined metaphases from three patients with chronic myeloid leukaemia and a typical Philadelphia chromosome with one chromosome 9 as the recipient to determine whether the 9q+ 22q- translocation is reciprocal. Good quality G-banded photographs of the chromosomes concerned were subjected to light absorption density analysis. This provided enlarged tracings corresponding to the relevant chromosome regions and so facilitated accurate measurement. This technique has unambiguously shown that the typical Philadelphia chromosome results from a reciprocal translocation and that probably no material is gained or lost in the exchange. Furthermore, in a total of six patients for whom sequential G and C banding was performed, the chromosome 9 with the largest block of centromeric heterochromatin received the translocated material. We offer tentative explanations for this curious observation.     

Coastal dune stability: The effect of meteorological conditions and vegetation

Quantitative investigations and research conducted along the north coast of New South Wales, Australia are evaluated with respect to coastal processes, coastal alignment, meteorological data, dune dimensions, dune vegetative cover, development on the dunal area and dune management.The data available covered an assessment of the extent of dune instabilities, an assessment of long term coastline movements, a study of the effect of a cyclone and storm surge, and an assessment and evaluation of a phase of extreme coastline erosion. Specific situations are described and evaluated within the above context. The evaluations are used to determine the extent of coastal dune areas required to be designated as buffer zone in land use planning. The extent of the zone required is dependent upon expected magnitude of wave erosion. Magnitude of wave erosion was found to be proportional to the interaction of coastal processes during periods of extreme erosive factors and the beach dune characteristics for the particular section of coastline. It was found that man's influence on this natural interaction can be a dominating factor in determining beach dune characteristics and therefore the magnitude of wave erosion. — management of the beach dunal area to maintain an acceptable dynamic equilibrium of the beach dune line by a vegetated sand dune of specific dimensions is possible despite weather conditions, if a designated buffer zone is maintained.Presented at the Seventh International Biometeorological Congress, 17–23 August 1975, College Park, Maryland, USA.