Modelling advection of cod eggs and larvae on the Newfoundland Shelf

We investigate interannual variations in dispersion for the drift and retention of cod eggs and larvae on the Newfoundland Shelf using a two-dimensional Lagrangian tracking model. The velocity field for the drift model is obtained from a diagnostic calculation of objectively analysed density data. Time-dependent currents are generated using an inertial-current slab model driven by observed winds. Eggs and larvae are treated as passive drifters seeded in a dispersion model of the Newfoundland Shelf region. We identify favourable and unfavourable zones of retention on the Newfoundland Shelf. We show that northerly, shelf-break spawning locations are more favourable than southerly shelf-break spawning locations for northern cod, ( Gudus morhua , in NAFO divisions 2J3KL).     

U.S. Economic Growth vs. Environmental Conditions

A widely-held belief is that stricter environmental regulations stifle economic growth. To determine empirically the effect of environmental conditions and policies on state-level per capita income growth, a Barro-type economic growth model was estimated for the years 1982 to 1991, which correspond to two consecutive troughs in the business cycle. States with better environmental conditions had significantly higher income growth rates during this period. At the same time, stricter environmental policies did not significantly depress income growth. Data used include recently developed, consistent measures of environmental policy and quality for individual states, as well as data from the 1980 U.S. Census and Bureau of Economic Analysis.     

Hormology in nutrition

Discrepancies in the growth curves for the sodium requirement of the cricket indicate that hormology may play an important role in the response to essential nutrients as well as to toxic compounds. Differentiation between stimulation of growth by a nonnutritive action and support of growth by an essential nutrient is difficult.     

Subtotal Canine Prostatectomy with the Neodymium: Yttrium-Aluminum-Garnet Laser

A technique was developed for subtotal prostatectomy in dogs with the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. In six normal dogs, full-thickness necrosis of the prostate occurred if the central-lateral region within 5 mm of the urethra was photoablated at 60 watts for 1 second. Moderate to superficial necrosis occurred when the prostate within 5 mm of the urethra was photoablated at 35 watts for 2 seconds or 60 watts for 0.5 second. At necropsy, leakage of the urethra occurred in two dogs at sites treated at 60 watts for 1 second. In a clinical study, complications associated with subtotal prostatectomy with the Nd:YAG laser (n = 6) were compared with complications associated with prostatic drainage (n = 6) in dogs with prostatic disease. Intraoperative death (2/6 dogs) and nocturnal incontinence (4/4 surviving dogs) occurred with subtotal prostatectomy. Uncontrolled prostatic infection (2/6 dogs) occurred with prostatic drainage and resulted in the death of one dog on day 11. Four of five dogs surviving prostatic drainage developed recurrent urinary tract infection.     

Tick (Ixodes holocyclus) paralysis in the dog – quantitative studies on immunity following artificial infestation with the tick

SUMMARY Beagles have been immunised against the paralysing effects of the Australian paralysis tick Ixodes holycyclus by allowing female ticks to feed on these dogs. Complete immunity to the toxic effects of lethal numbers of feeding ticks has persisted in these beagles for at least 53 weeks and in similarly-immunised foxhounds for at least 102 weeks, during which periods the beagles and foxhounds were kept free of ticks. Serum antitoxin titres increased to a maximum value (hyperimmunity) of 46 antitoxin units/mL with a minimum number of 11 ticks feeding simultaneously. Titres declined to a low level after 12 to 14 weeks of freedom from tick infestation but increased again on reinfestation with ticks. Large numbers of ticks (up to 60) appeared to be required after several stimulation/relaxation cycles to obtain hyperimmune levels of antitoxin in serum. The serum antitoxin titre appeared to be a good indicator of effective immunity to tick paralysis during the initial development of hyperimmunity but was less indicative thereafter, as dogs whose serum antitoxin titres had reached an apparent maximum remained immune to tick paralysis after titres had decreased to low levels. There was no evidence of cutaneous hypersensitivity or any other tick rejection mechanism that could account for this effect.     

A Retrospective Study of Inguinal Hernia in 35 Dogs

Inguinal hernia was associated with trauma in five dogs and was considered nontraumatic in 30 dogs. There were 11 males, 13 intact females, and six spayed females with nontraumatic inguinal hernia. Six dogs had bilateral hernias. Five dogs were younger than 4 months at the time of diagnosis. In 11 older dogs with nontraumatic inguinal hernia, the hernias were identified less than 7 days before surgical repair; in 14 older dogs, the hernias had been recognized for 1 to 60 months. Clinical signs in dogs without small intestinal incarceration were usually limited to a visible or palpable mass without pain or systemic illness. Hemiorrhaphy approaches included inguinal, midline with contralateral ring evaluation, and celiotomy with or without inguinal exposure. Fat and omentum were the most common hernial contents. Small intestine was within the hernias of 12 dogs. Six dogs had nonviable small intestine. Postoperative complications included two incisional infections, one incisional dehiscence, two cases of peritonitis and sepsis associated with bowel leakage after intestinal resection and anastomosis, and one hernia recurrence. The overall prevalence of postoperative complications was 17%, and the mortality rate was 3%. Vomiting for 2 to 6 days was predictive of nonviable small intestine. Dogs younger than 2 years were at 11 times greater risk for nonviable small intestine than dogs older than 2 years. Four of five dogs with nontraumatic inguinal hernia and nonviable small intestine were intact males, whereas none of 13 intact females were affected. Only one of 14 dogs with longstanding hernias had nonviable small intestine.     

In Vitro Loss of Tensile Strength and Elasticity of Five Absorbable Suture Materials in Sterile and Infected Canine Urine

The loss of breaking strength and elasticity of five absorbable suture materials (polydioxanone [PDS-II], polyglycolic acid [PGA], polyglactin 910 [PG-910], polyglyconate [GTMC], and chromic gut) after in vitro incubation in sterile, Escherichia coli- and Proteus mirab/tfs-inoculated canine urine was studied. Biomechanical testing, in a controlled environment, was performed during the 28-day study period. Polydioxanone and chromic gut retained greater than 90% of their original strengths after 28 days of incubation in sterile urine and 87% of original strengths in E. co//-inoculated urine. Polyglyconate retained 24% and 18% of original strength, respectively, after incubation in sterile and E. co/i-inoculated urine for 28 days. Polyglycolic acid and PG-910 retained less than 30% of original strength in sterile urine and only 7% in E. co/i-inoculated urine after 21 days of incubation. In P. m/rabi/is-inoculated urine, loss of tensile strength and elongation was significant for all suture materials. Polyglycolic acid and PG-910 lost all strength after 24 hours of incubation. Polydioxanone lost all strength after 7 days of incubation, whereas GTMC retained 19% at day 7. Chromic gut retained 78% at day 7 and 16% after 21 days of incubation, however, the absence of normal phagocytic destruction of chromic gut in this in vitro study may have artificially elevated these values. In sterile urine with chemically modified pH, loss of strength and elongation was greater in alkaline urine than in neutral or acidic urine for all types of suture materials.     

Intraoperative Biopsy and Microscopy During Exploratory Laparotomies

Intraoperative biopsy and microscopy were evaluated, retrospectively, in 23 exploratory laparotomies. After comparing the surgical impression to the microscopic diagnosis obtained during surgery, the use of intraoperative cytologic and frozen section examination altered the surgical plan in 13 cases and reinforced the surgical plan in 10 cases. No cases had an intraoperative microscopic diagnosis that differed from the postoperative histologic examination of paraffin sections. Recommendations for selecting cases and for using intraoperative biopsy and microscopy are included.