Splenectomy of the fetal lamb early in development as a model for congenital asplenia.

BACKGROUND: The liability to overwhelming infection of children lacking a spleen either as a result of its congenital absence or because of splenectomy, has been frequently documented. Although there have been numerous studies of the consequences of experimental splenectomy in postnatal animals, this is the first study of the effects of this operation in early fetal life. METHODS: A technique is described for microsurgical removal of the spleen from fetal lambs approximately one-third of the way through gestation, when the fetus is approximately the size of a mouse. Lambs that had been splenectomized in utero were submitted to haematological examination in postnatal life and were challenged with pneumococcal polysaccharide to test their immunological competence. RESULTS: Lambs in which splenectomy had been performed close to the gestational age of initiation of the splenic contribution to differentiation of immune and haemopoietic systems, exhibited insignificant deviations from normality in postnatal life. CONCLUSION: Provided the spleen is removed from the fetal lamb sufficiently early in gestation, it is possible for other lymphoid tissues to compensate for most of the deficiencies that would be anticipated in animals lacking a spleen. In this experiment, splenectomy was performed at approximately the developmental stage equivalent to that at which the spontaneous interruption of development that leads to human congenital asplenia occurs. The absence of major postnatal abnormalities observed in these lambs reinforces the significance of the associated abnormalities in the development of the clinical deficits observed in children with spontaneous asplenia.

Repetitive stress injury: diagnosis or self-fulfilling prophecy?

* The vague definitions of so-called repetitive stress injuries are indicative of the fact that scientific studies have failed to show that repetitive motion causes injury. * Given the uncertainty about causation, work-related musculoskeletal disorders (WRMSDs) is a more readily accepted term to describe these phenomena. * There is little doubt that most ergonomic interventions increase comfort in the work environment, which is of great benefit to the worker. Many proponents of ergonomics assert that the elimination of certain risk factors related to force, repetition, and posture can prevent or even cure work-related musculoskeletal disorders of the upper extremity. However, there is little scientific support for this position. * Undue reliance on ergonomics to treat musculoskeletal disorders, to the exclusion of proper diagnosis and attention to medical and health risk factors, can have adverse consequences for the patient. * Science rather than politics and public policy should determine what causes injury and disease. * The failure of numerous plaintiffs in litigation regarding repetitive stress injury due to use of computer keyboards is important because, when judges and lay jurors were presented with both sides of the issue, they rejected these claims in a forum (the judicial system) that traditionally compensates individuals bringing so-called mass-tort cases.

History and physical examination to estimate the risk of ectopic pregnancy: validation of a clinical prediction model.

STUDY OBJECTIVE: To prospectively validate a clinical prediction model for ectopic pregnancy (EP). METHODS: Prospective cohort with 14-month derivation and 12-month validation phases. All hemodynamically stable, first-trimester patients with abdominal pain or vaginal bleeding who presented to a military teaching hospital emergency department underwent follow-up until an outcome of intrauterine pregnancy (IUP) or EP was established. Patients were separated into the high-risk group, defined as having either peritoneal signs or definite cervical motion tenderness; intermediate-risk group, defined as the presence of pain or tenderness, other than midline cramping, plus absence of fetal heart tones, and absence of tissue visible at the cervical os; and low-risk group (neither high- nor intermediate-risk) using recursive partitioning. RESULTS: Summarizing both phases, 915 patients had 845 (93%) IUPs and 70 (7.6%) EPs, with 18 (1.9%) lost to follow-up. The clinical prediction model classified 75 (8.2%) into the high-risk group (sensitivity 31%, 95% confidence interval [CI] 21% to 44%; specificity 94%, 95% CI 92% to 95%); and 644 (70%) in the intermediate-risk group (sensitivity 98%, 95% CI 89% to 100%; specificity 25%, 95% CI 22% to 29%). The remaining 196 (21%) patients who met neither high-risk nor intermediate-risk criteria were classified into the low-risk group. On the basis of EP prevalence of 7.7%, the risk of EP was less than 1% (95% CI 0% to 3%) for the low-risk group, 7% (95% CI 5% to 10%) for the intermediate-risk group, and 29% (95% CI 19% to 41%) for the high-risk group. CONCLUSION: This clinical prediction model is useful for estimating the risk of EP in first-trimester patients, particularly when ancillary testing is equivocal or not readily available.

Derivation of a clinical prediction model for the emergency department diagnosis of ectopic pregnancy.

OBJECTIVE: To derive a clinical prediction model for estimating the pretest probability of ectopic pregnancy in ED patients with first-trimester abdominal pain or vaginal bleeding. METHODS: All hemodynamically stable first-trimester patients presenting to the ED of a tertiary care military teaching hospital over a 14-month period with a chief complaint of abdominal pain and/or vaginal bleeding had clinical data coded prior to determining outcome. They were then followed longitudinally until a criterion standard pregnancy outcome was established. RESULTS: Of the 486 patients enrolled, 280 (58%) had viable intrauterine pregnancies, 167 (34%) had nonviable intrauterine pregnancies, and 39 (8%) had ectopic pregnancies. Using a recursive partitioning model, a high-risk group was derived (that was separated from intermediate and low-risk groups), consisting of patients with abdominal peritoneal signs or definite cervical motion tenderness, with a sensitivity of 31% (95% CI: 17-48%), a specificity of 93% (95% CI: 90-95%), a positive likelihood ratio of 4.3, and a negative likelihood ratio of 0.74. A low-risk group, consisting of patients with either fetal heart tones or tissue at the cervical os, or the absence of pain other than midline menstrual-like cramping and lacking any pelvic tenderness, was differentiated from an intermediate-risk group, with a sensitivity of 96% (95% CI: 81-100%), a specificity of 22% (95% CI: 18-26%), a positive likelihood ratio of 1.2, and a negative likelihood ratio of 0.17. CONCLUSION: A clinical prediction model for estimating the probability of ectopic pregnancy in ED patients has been derived. It may prove to have practical clinical application for estimating pretest probability of ectopic pregnancy as well as assisting in medical decision making when laboratory and ultrasonographic findings are nondiagnostic. Clinical application should await prospective validation in an independent sample.

Cellular interactions during the development of autoimmunity in a fetal lamb model of self-antigen deprivation.

Anti-thyroid autoimmune responses have been examined in fetal lambs, the immune systems of which had matured in the absence of exposure to thyroid-specific antigens. The lymphocytic infiltrate in self-thyroid tissue reintroduced into autoimmune lambs showed well-differentiated B and T cell domains. However, T cells from these fetuses were not sensitized against ovine thyroglobulin nor did serum antibodies appear against ovine thyroglobulin or thyroid peroxidase. In the light of these observations, it is inferred that the primary abnormality in the immune systems of fetuses deprived of exposure to thyroid autoantigens is likely to be a failure of the development of a normal T cell subpopulation responsible for down-regulation of autoreactivity. It is also concluded that overt autoimmunity develops only when these fetuses are challenged with thyroid tissue and that B cells may undertake an antigen-presentation role in its induction.

An assessment of absorbable lysine requirements in lactating cows.

Two experiments were conducted to ascertain lysine required for maintenance and milk production in lactating dairy cows. Multiparous Holstein cows fitted with abomasal cannulas were utilized in a replicated 3 x 3 extra-period Latin square design and infused with 0, 45, or 90 g of L-lysine-HCl daily (Experiment 1). In Experiment 2, 12 cows were utilized in a 5 x 5 Latin square design (with 2 replacement cows) and infused with 0, 22.5, 45, 90, and 180 g of L-lysine-HCl daily. Cows were housed in comfort stalls, milked at 0600 and 1700 h, exposed to a 16:8 h light:darkness cycle, and fed for ad libitum intake a 15.7% CP diet formulated to contain approximately 75% of dietary protein from corn-based feed ingredients. Milk yield was not affected in Experiment 1, but milk production increased linearly with lysine infusion level in Experiment 2. A linear response in daily yield of milk protein to lysine infusion was observed in both experiments. As lysine infusion increased, coccygeal plasma lysine concentrations tended to increase in Experiment 1, but in Experiment 2 free lysine increased linearly and quadratically in coccygeal plasma and increased linearly in plasma from the subcutaneous abdominal vein. The quadratic response in plasma free lysine (Experiment 2) suggested that lysine was the limiting AA for milk production from the composite protein flow to the small intestine. Using break-point analysis of plasma free lysine, it was estimated that the additional amount of abomasal lysine required to satisfy requirements was 64 g/d in cows producing about 30 kg of milk daily. Although additional lysine above microbial and undegraded intake protein lysine flow stimulated milk protein production, conversion efficiency to milk protein lysine was low.

Influence of dietary protein sources on the amino acid profiles available for digestion and metabolism in lactating cows.

Six lactating Holstein cows, fitted with T-type cannulas in the proximal duodenum, were used in a replicated 3 x 3 Latin square design to determine influence of supplemental protein on amino acid profiles of duodenal chyme and plasma. Protein sources were blood meal, corn gluten meal, and cottonseed meal, which furnished approximately 46% of the total protein in corn-grain corn silage diets. Markers were 15N to estimate rumen bacteria and chromic oxide to estimate nutrient flow. Dry matter intake was lowest on blood meal. Duodenal flow of N exceeded N intake 23% on blood meal and corn gluten meal. Percentages of organic matter and protein digested in the rumen were 56.5, 41.8; 61.2, 53.4; and 50.6, 56.2 for the respective diets. Variation in patterns of amino acids flowing to the duodenum, but not in coccygeal blood, closely reflected dietary differences with six of eight essential amino acids highest for the same treatment in both diet and duodenal chyme. Essential amino acids in least abundance for milk production, measured by mammary extraction coefficients, differed among diets. We conclude that supplemental protein source influences greatly the quantity and pattern of amino acids available for digestion in lactating dairy cows.

Effects of dietary amines on small intestinal variables in neonatal pigs fed soy protein isolate.

Six litters of newborn crossbred piglets were utilized to examine 1) the effects of substituting 20% of the protein of an all-milk protein liquid diet with a soy protein isolate (milk-soy diet) on small intestinal variables and 2) the effects of supplementing this milk-soy diet with 25 g of either putrescine or ethylamine per kilogram diet on small intestinal variables. Small intestinal xylose absorption tended to increase from wk 1 to wk 2 of age in pigs fed the milk, putrescine and ethylamine diets, but not in pigs fed the milk, putrescine and ethylamine diets, but not in pigs fed the unsupplemented milk-soy diet. Crypt depth in pigs fed the milk-soy diet tended to be less (9.4%; P greater than .10) than the crypt depth in pigs fed the other diets, but mitotic index was not different (P greater than .10) among diets. Mucosal protein, DNA and RNA concentrations and mucosal brush border sucrase and cytosolic dipeptidase activities tended to be least in pigs fed the putrescine and ethylamine diets. Concentration of mucosal putrescine was greatest (P less than .002) in the distal regions of the small intestine of pigs fed putrescine. Mucosal ornithine decarboxylase activity was inhibited by putrescine (P less than .02), but it was not affected by the soybean protein isolate used in this study. Supplementing soy protein isolate diets with amines may enhance intestinal absorption and enterocyte proliferation.

Effects of dietary amines on the small intestine in calves fed soybean protein.

An experiment was conducted using 16 Holstein male calves from 4 to 21 d of age to compare 1) the effects of an all-milk protein milk replacer (MPR) and a milk replacer with 20% of the protein from soy protein concentrate (SPC) on morphological and enzymic small intestinal variables, and 2) the effects of SPC plus putrescine (SPP) or SPC plus ethylamine (SPE) on intestinal variables. Small intestinal absorption, based on xylose absorption tests, was greater in calves fed MPR than in those fed SPC (P less than 0.01) and was intermediate in SPP- and SPE-fed calves. Small intestinal segments were surgically excised from the proximal and distal jejunum of all calves at 7, 14 and 21 d of age. Villus length tended to be greatest in calves fed MPR, and mitotic index was least in SPC-fed calves (P less than 0.05). Mucosal protein concentration was 46, 41, 44 and 44 micrograms/mg mucosa for calves fed MPR, SPC, SPP and SPE, respectively. The ratio of mucosal protein:RNA was greatest in calves fed MPR, least in those fed SPC at d 7 (P less than 0.01) and d 14 (P less than 0.05), and intermediate in calves fed SPP and SPE. In proximal jejunum, activity of mucosal ornithine decarboxylase (ODC, EC 4.1.1.17; the rate-limiting enzyme in polyamine biosynthesis) in calves fed SPP was less than 50% of that in calves fed MPR, SPC or SPE. The activity of lactase (EC 3.2.1.108) and ODC in distal jejunum was 50% less in calves fed soybean protein than in those fed MPR.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritive value of potato processing wastes in total mixed rations for dairy cattle.

The nutritive value of wet potato processing waste for dairy cattle was determined in two experiments. In Experiment 1, rations contained, on a dry matter basis, 0, 10, 15, and 20% potato waste and were substituted for high moisture corn in diets for 32 lactating Holstein cows for 12 wk. Substituting potato waste for corn did not significantly affect milk yield, milk composition, milk production persistency, or dry matter intake. Cows fed 20% potato waste tended to decrease in milk fat percent and to shift molar proportions of rumen volatile fatty acids toward a decrease in acetate: propionate ratio. In Experiment 2, six steers were used in a 3 X 3 Latin square design to test digestibility and nitrogen utilization of potato waste substituted for high moisture corn at 0, 10, and 20% of the ration dry matter. A second group of four steers with rumen fistulas were used in a 4 X 4 Latin square to test rumen fermentation parameters. Diets contained 0, 10, 20, and 30% potato wastes and were similar to Experiment 1. Potato waste did not significantly affect digestibility of crude protein or dry matter, but at 20% substitution digestibility of acid detergent fiber decreased. Rumen ammonia, acetate, acetate to propionate ratios, and total volatile fatty acids were lower at high intakes of potato waste and pH was increased. The shift in rumen fermentation when large amounts of potatoes were fed explains the depressed butter fat on these rations.

Influences of methionine hydroxy analog on milk and milk fat production, blood serum lipids, and plasma amino acids.

Feeding for 150 days of 25 g per day of methionine hydroxy analog was tested on 100 cows (52 treated and 48 controls) in the Brigham Young University herd. Effect of days after parturition of initiating methionine hydroxy analog feeding also was observed. Milk yields were not affected by methionine hydroxy analog, but fat percent and fat yields were increased 21 and 17% by the additive. Abnormally low milk fat by control cows (2.84%) magnified the response to methionine hydroxy analog feeding. Feeding methionine hydroxy analog beginning 0 to 12 days postpartum elicited much larger increases of milk fat than started later (17 to 102 days). Blood from the coccygeal vein of 20 cows from each treatment had 10% more triglycerides from cows fed methionine hydroxy analog than from control cows. Increases of arterio-venous differences across the mammary gland of triglycerides and lipoproteins of blood serum suggested that increases of milk fat could have resulted from greater uptake of performed fat by the udder. Feeding methionine hydroxy analog increased methionine, isoleucine, and leucine in serum of coccygeal vein, but methionine was the only amino acid with significantly higher arteriovenous differences across the mammary gland.

Neglect and abuse of children: historical aspects, identification, and management.

The dentist's role primarily involves awareness of the problem of maltreatment, a method of approach to identify and report suspected cases, the documentation of the injuries or neglect which have been observed, and follow-up of any orofacial injuries. Orofacial trauma is present in up to one half of the reported cases of child abuse and consists of bruises, burns, lacerations, and fractures of teeth and jaws. Further studies in the dental field are needed to delineate the types and incidences of orofacial injuries and their relationship to child abuse. Dentists and all professionals must work together, if adequate services are to be provided to protect children and rehabilitate families.