The "barker" (neonatal respiratory distress) syndrome in the pig: its occurrence in the field.

A new syndrome, characterised by acute respiratory distress and by abnormalities of the skin, hair and thyroid, was the apparent cause of neonatal death in 35 (24 per cent) of 146 piglets sired by a large white boar in four small commercial pig units. The syndrome appears to be of genetic origin, inherited as an autosomal recessive trait. Its similarities with the respiratory distress syndrome (RDS) of the newborn infant and the "barker" syndrome of the newborn foal are discussed.     

Biochemical genetics of oxidative resistance to diazinon in the house fly

The genetics and biochemistry of oxidative resistance to diazinon were investigated in a diazinon-resistant strain of the house fly, Musca domestica L. The resistant strain was crossed with a multimarker susceptible strain and substrains containing portions of the resistant strain genome were prepared. Resistance, microsomal oxidase, and cytochrome P-450 spectral characteristics were then compared in the different strains. The major gene for resistance to diazinon is semidominant and is located on chromosome II, 13 crossing over units from the recessive mutant stubby wing. Additional resistance genes occur on chromosome II and on other chromosomes as well. Resistance to diazinon was introduced into a susceptible mutant-marked strain via genetic crossing over. Increases in parathion oxidase, total and P-450-specific N- and O-demethylase activity, and resistant strain type I binding spectrum were introduced along with resistance, indicating genes controlling these parameters and resistance are either identical or closely linked. No increase in activity of cytochrome P-450 itself was introduced into the mutant strain. Additional genes controlling the amount of cytochrome P-450 and several spectral changes characteristic of the resistant strains are apparently controlled by genes located at different loci on chromosome II. Resistance factors on other chromosomes are also present, but were not characterized.     

Comparative enzyme activities and cytochrome P-450 levels of some rat tissues with respect to their metabolism of several pesticides

Cytochrome P-450, A- and B-esterase, amidase, and glutathione S-aryl transferase were assayed in the postmitochondrial centrifugal fraction, microsomes, and supernatant of rat liver, lungs, kidneys, and testes. Liver microsomes contained the highest P-450 levels and A-esterase activity. B-esterase activity was more generally distributed and higher in the microsomal tissue fractions. Microsomal amidase activity was highest in rat lung and lowest in the liver (per mg protein). Glutathione S-aryl transferase activity was highest in the liver. The in vitro metabolism of carbaryl, phosphamidon, and chlorotoluron by the various centrifugal fractions revealed many differences. Carbaryl metabolism was greater in the liver microsomal fractions than in any other preparation. 1-Naphthol was the major metabolite in all tissue fractions. Although very little metabolism of phosphamidon occurred in the rat, metabolism in the rat liver postmitochondrial fraction was slightly higher with respect to the production of metabolites than in the supernatant and microsomes combined. Chlorotoluron was not metabolized by any of the tissue fractions of the rat. At least a low level of activity toward some compounds was observed in all tissues, but this study confirmed that the liver was the most active metabolizing tissue as well as having the highest levels of enzymatic activity usually associated with pesticide metabolism.     

The hen's egg: Shell cracking at impact on a heavy,stiff body and factors that affect it

1. Eggs from hens of three strains were dropped on to a heavy, stiff, smooth, plane body with impact at the equator of the shell; the height of drop, h_c, just sufficient to produce shell failure was measured and the corresponding impact velocity, v_c, calculated.

2. A small but commercially important percentage of the well‐formed eggs of one strain cracked when h_c was as low as 3–3 mm and v_c 250 mm/s.

3. Characteristics of the egg found to affect h_c and v_c included the overall thickness of its shell, thickness of its weak inner shell layer and average shell curvature, all measured at the point of impact, and its weight; its age also had a small effect (additional to that mediated through loss of weight); so did the degree of shell ridging.

4. No effect of shell colour was found.

5. Shell damage was typically a single hair‐crack that ran either round the equator or towards a pole.     

Agammaglobulinemia in a horse with evidence of functional T lymphocytes.

Agammaglobulinemia was diagnosed in a 1-year-old Thoroughbred horse on the basis of the following observations: (1) absence of serum immunoglobulins M, A, and G(T); (2) small amounts of serum immunoglobulin G (16 mg/100 ml); (3) absence of specific antibody in the serum of the horse following immunization and challenge exposure to 2 antigens; (4) absence of plasma cells, primary follicles, and germinal centers in a lymph node removed after antigenic stimulation; (5) absence of "natural" serum antibodies to rabbit-erythrocytes which were easily detectable in age-matched control horse serums; and (6) increased susceptibility to infections. There was evidence of functional cell-mediated immunity which included a skin response to injected phytolectins, skin response to antigen challenge following sensitization, and in vitro proliferative response of lymph node cells to phytohemagglutinin. An intact cell-mediated immune response was also supported by the observation that the horse lived to 17 months of age without antibody production, whereas horses with an absence of both antibody production and cell-mediated immunity (combined immunodeficiency) die by 4 months of age without immunologic intervention. The known features of agammaglobulinemia in this horse are similar to those in sex-linked agammaglobulinemia in persons and are unique among the immunodeficiences described in other animals.     

The effect of the administration of Solanum malacoxylon on the chick.

Replacement of the drinking water of chicks maintained on a normal mixed protein diet with an aqueous extract containing the equivalent of 5 g of the dried leaves of Solanum malacoxylon (DLSM) per 100 ml for one month produces a hypercalcaemia (23-49 per cent), hypomagnesamia (28-37 per cent), hypophosphataemia (26-34 per cent), hypouricaemia (29-34 per cent) and a decrease in plasma alkaline phosphatase activity (54-98 per cent). The ash content of the defatted, dried tibiae and the body weight of the DLSM treated chicks were also significantly lower (37-7 per cent and 17-79 per cent respectively) than the corresponding values for the untreated birds. The results obtained are similar to those reported for hypervitaminosis D3 in the chick.     

Effects of female sex hormones on uterine motility and reactivity to oxytocin in goats.

Uterine motility was recorded for several weeks in 10 ovariectomised goats, using small intra-uterine balloons, to study the effects of female sex hormones on uterine activity and reactivity to oxytocin. Oestradiol stimulated uterine contractions and increased both the sensitivity and intra-uterine pressure response to oxytocin. When progesterone was administered in addition to oestradiol, spontaneous uterine motility became irregular with low amplitude contrations; the sensitivity and reactivity to oxytocin was significantly depressed.