Showing papers by "Monash University published in 1981"

Pregnancies in humans by fertilization in vitro and embryo transfer in the controlled ovulatory cycle.

Abstract: Normal pregnancies have been established in four women with tubal infertility by fertilization in vitro, embryo culture, and embryo transfer after stimulation of follicular growth with clomiphene citrate. In three of these women the time of oocyte maturation was controlled by human chorionic gonadotropin. This procedure for the control of ovulatory response has many advantages when compared with the previously successful method of using the natural ovulatory cycle.

Evidence for an action of morphine and the enkephalins on sensory nerve endings in the mouse peritoneum

Abstract: 1 A modification of the abdominal constriction test in mice has been developed, and used to study the antinociceptive effects of morphine and several related drugs. In most experiments, acetic acid (0.6% i.p.) was used as the nociceptive stimulus, and in a few cases, acetylcholine (3.2 mg/kg i.p.) was used. When the abdominal constriction response had reached a maximum, the drugs under test were given intraperitoneally, and their ability to decrease the number of abdominal constrictions was determined, beginning immediately after its administration. The aim of this study was to investigate the possibility that morphine and its congeners may produce an antinociceptive effect by an action within the peritoneum. 2 It was found that morphine was an extremely potent antinociceptive agent in this modified test, with an ID50 of 5.4 × 10-9 mol/kg (1.54 μg/kg). Codeine and pentazocine were about 40 times less active and oxymorphine was about twice as potent as morphine. Met- and Leu-enkephalin were also potent but their action diminished very rapidly with time. Ketocyclazocine was the most potent substance tested, and had an ID50 value of 1.26 × 10-10 mol/kg (0.036 μg/kg). All the drugs tested produced their maximal effect within 1 or 2 min of administration. 3 Pretreatment of the mice with naloxone caused a dose-dependent shift to the right of the dose-response curve to morphine. The pAx plot was linear over part of the range, with a slope of -1.02 and the `apparent pA2' value was 6.14. Naloxone was much less effective in antagonizing Met-enkephalin, and caused a slight potentiation of ketocyclazocine and pentazocine and of cocaine, which was used for comparison. 4 Pretreatment of mice with morphine, 3 h earlier, caused a marked tolerance to a subsequent dose of morphine, and a potentiation of the antagonist potency of naloxone. However, there was little cross-tolerance between morphine and Leu-enkephalin. 5 It is concluded that morphine and its congeners can produce an antinociceptive effect by an action within the mouse peritoneum, presumably by interacting with one or more types of opioid receptors which may be situated on sensory nerve endings.

Spatial ability, visual imagery, and mathematical performance

Abstract: 116 Foundation Year Engineering Students, at the University of Technology, Lae, Papua New Guinea, were given a battery of mathematical and spatial tests; in addition, their preferred modes of processing mathematical information were determined by means of an instrument recently developed in Australia by Suwarsono. Correlational analysis revealed that students who preferred to process mathematical information by verbal-logical means tended to outperform more visual students on mathematical tests. Multiple regression and factor analyses pointed to the existence of a distinct cognitive trait associated with the processing of mathematical information. Also, spatial ability and knowledge of spatial conventions had less influence on mathematical performance than could have been expected from recent relevant literature.

A morphologic and morphometric analysis of fetal lung development in the sheep.

Abstract: In the sheep, fetal lung development proceeds to a later stage of maturity than in smaller laboratory animals. Of the four stages in pulmonary development recognizable in this species - embryologic, pseudoglandular, canalicular, and aveolar - the latter three are described in the present study using histologic, morphometric, and ultrastructural techniques. During the pseudoglandular stage, the major airways developed centrifugally. Cartilaginous, glandular, muscular, vascular, and neural elements were present in major airway walls from an early age. During the canalicular stage, volume expansion of the lung was accomplished by rapid growth of large terminal spaces. In the final stage, alveoli were formed following subdivision of the large terminal spaces by alveolar crests. The alveolar lining epithelium differentiated during the latter two stages producing a large increase in alveolar surface area, particularly during the alveolar stage; a large increase in pulmonary capillary surface area also accompanied alveolar development. Thus, just prior to birth, the fetal sheep lung has a well-developed air-way system and alveolar network, in preparation for postnatal gas exchange.

The meanings of r- and K-selection

Abstract: This paper catalogues several different dichotomies that have all been termed r- and K-selection. The status of the concept of r- and K-selection is discussed and a more restricted usage of the terms is recommended.

Structural Changes Associated with Freezing of Bovine Embryos

Abstract: The structural changes associated with freezing and thawing were examined in bovine embryos at three developmental stages: Day 5, Day 7, and Day 13 (Day 0 day of estrus). Embryos collected at DayS had 8-16 cells, and contained numerous vesicles and primitive junctional regions between some adjacent blastomeres. After cooling to 4#{176}C, the distribution of organelles within blastomeres as well as the spacial arrangement of blastomeres was disrupted. Day 7 embryos were at the early blastocyst stage and contained an intact ring of trophoblast cells enclosing a disc of embryonic cells. Adjacent trophoblast cells were attached by a region of junctional complexes which were structurally unaffected by freezing. Damage to blastocysts after freezing included loss of the integrity of the trophoblast plasma membrane, leading to collapse of the blastocoele. When some collapsed blastocysts were cultured for 24 h after thawing, a smaller intact ring of trophoblast cells had reformed around the embryonic cells and debris from cryoinjured cells was excluded from the blastocoele. Day 13 embryos contained three morphologically distinct cell types: a Layer of trophectoderm, a disc of embryonic cells, and a continuous layer of endoderm cells surrounding the blastocoelic cavity. After freezing and thawing, the embryonic cells were structurally intact while the trophectoderm had substantial damage to all cell components� In conclusion, cryoinjury in bovine embryos may be selective for one cell type within an embryo, and its extent and nature are dependent on developmental stage.

Familial euthyroid thyroxine excess: an appropriate response to abnormal thyroxine binding associated with albumin.

Abstract: Responses of the pituitary-thyroid axis and T4 binding to plasma proteins were studied in three kindreds with familial euthyroid T4 excess, an autosomal dominant condition in which affected subjects have high concentrations of plasma T4 with a high free T4 index, but normal free T4 by equilibrium dialysis. Treatment of affected subjects with exogenous T4 or T3 led to gradual suppression of TSH secretion when the free level of T4 or T3 increased above normal. When total T4 was reduced toward normal by potassium iodide treatment or previous subtotal thyroidectomy, the findings suggested mild hormone deficiency. In affected subjects from all three families, equilibrium dialysis showed increased [125I]T4 binding, with evidence of abnormal high capacity binding when an excess of unlabeled T4 was added. In contrast, T3 binding showed no major abnormality. Serum concentrations of T4-binding globulin, prealbumin, and albumin were normal, but gel electrophoresis and immunoprecipitation of binding proteins indicated that 25-30% of tracer [125I]T4 was albumin bound (normal, 10-12%). Abnormal binding, studied by an adsorption separation system in the presence of T4 excess, was inhibited by increments of barbitone. These findings suggest that T4 excess is an appropriate response to abnormal T4 binding so as to maintain normal free T4. The excess bound T4 is associated with a normal quantity of albumin. The basis for increased T4-albumin binding remains to be determined.

The experimental ductile deformation of polycrystalline and single crystal pyrite

Abstract: Polycrystalline pyrite, deformed in triaxial compression tests at a confining pressure of 300 MPa, strain rates of 10 (super -4) sec (super -1) to 10 (super -5) sec (super -1) , and temperatures above about 450 degrees C, shortens by dislocation flow mechanisms. Above 500 degrees C dynamic recovery and recrystallization are important, and steady state flow is attained after 10 to 20 percent shortening. The dynamically recrystallized grain size (d) (in mu m) is related to the flow stress (Sigma ) by the relationSigma / G = k (d/b) (super -0.9) ,where k = 16.2, G = 7.8 X 10 4 MPa, and b = 5.42 X 10 (super -4) mu m. Below about 450 degrees C polycrystalline pyrite deforms by brittle mechanisms after less than a few percent strain by dislocation flow.The strength of polycrystalline pyrite decreases significantly with increasing temperature and decreasing strain rate. Over the temperature interval 500 degrees to 700 degrees C, at strain rates of 2 X 10 (super -5) sec (super -1) , the steady state flow stress drops from about 500 to 70 MPa.Pyrite single crystals shortened in the and orientations at 600 degrees C, about 10 (super -5) sec (super -1) , and 300 MPa confining pressure exhibit three-stage work-hardening behavior in which the stage 2 work-hardening rates are nearly as high as the elastic modulus. For shortening the yield stress (280 MPa) and the differential stress at the commencement of stage 3 (800 MPa) are several times larger than for shortening. The strength during shortening is comparable to that of the polycrystalline pyrite tested.The single crystal strength data, structural considerations, and transmission electron microscopy suggest that {100} and possibly {100} are major slip systems. The {110} dislocation glide may also be important but has a critical resolved shear stress several times higher than {100} glide.The present data indicate that pyrite can be considerably weaker and more ductile than indicated by previous studies, and that pyrite is likely to be deformed by dislocation flow mechanisms under a range of geologically realistic conditions.

Wind-Induced Lock-In Excitation of Tall Structures

Abstract: Circular and square tower models were tested in a boundary layer wind tunnel. At close to the critical reduced velocity and particularly at low values of structural damping, displacement dependent lock-in excitation was found to cause large increases in cross-wind displacement response, especially for the circular tower, in a suburban type wind model. Critical cross-wind response amplitudes were determined from the response characteristics. These response amplitudes represent the level of cross-wind response of a structure above which the response can not be accounted for by the random wake excitation process and that lock-in excitation is significant. A prediction procedure, which consists of a random excitation model and a sinusoidal lock-in excitation model, is described. Cross-wind response predicted by these models agreed well with the measured response.

A technique for assessing the composition and density of the macroinvertebrate fauna of large stones in streams

Abstract: A device for quantitatively sampling the macroinvertebrates of large stones in streams is described. In comparison to the usual method for sampling the fauna of large stones, (the lifting of stones upstream of a hand net), the present method accurately samples stonedwelling animals that are good swimmers. Details are given of a reliable method to measure the surface area of stream stones using thin plastic sheeting.

Surgery for constipation

Abstract: Over a period of 30 years a total of 27 patients were subjected to partial or complete colectomy and anastomosis for constipation. Cases fall into four groups: (a) functional constipation, (b) adult megacolon, (c) megasigmoid and (d) persistent Hirschsprung’s disease. The first two groups comprised 17 patients with resistant constipation, with or without megacolon or dolichocolon. Seven (41%) of these patients subsequently required operation for acute small-bowel obstruction due to adhesions. In two patients a permanent ileostomy was necessary for persistent rectal inertia after colectomy. The functional results in these first two groups were good. The third and fourth groups had similar presenting features; five had megasigmoid and in these resection of the sigmoid colon gave good results. The remaining five cases with proven Hirschsprung’s disease responded well to a pull-through resection (4) and to colectomy and anastomosis (1).

Disease-free survival and recurrence after resection of colorectal carcinoma.

Abstract: Recurrence data from a series of 1,315 colorectal cancer patients managed by one surgeon with potentially curative resection are presented. Complete follow-up information was available on 1,287 (98%) patients. At the time of the last recurrences, 164 and 232 months for rectal and colonic tumours respectively, the long-time recurrence rate was significantly (P = 0.001) higher for rectal tumours (42%) than for colonic (33%). Although local recurrences tended to be more common in rectal than in colonic tumours (18% compared to 15%), only those in contiguity with the operative area were significantly (P less than 0.005) more common in rectal tumours. Systemic recurrences were also significantly (P less than 0.025) commoner for rectal tumours. The greater recurrence rates in rectal tumours were associated with significantly (P less than 0.001) higher incidence of stage C tumours shorter recurrence-free survival in rectal stage C tumours (P = 0.001) and higher incidence of pulmonary metastases (P less than 0.001).

Factors affecting the variability of semen analysis results in infertile men

Abstract: UNLABELLED Infertile men who had 3 or more semen analyses performed in one laboratory were placed in 2 groups (I) oligozoospermic group (n = 106), mean sperm concentration between 1 and 20 million/ml (II) asthenozoospermic group (n = 71), mean sperm concentration greater than 20 million/ml, and mean motility less than 60%. With increasing durations of abstinence from ejaculation before the tests there were significant increases in semen volume and sperm concentration. Semen volume increased over the first 4 days to a similar extent in both groups. Sperm concentrations increased over 15 days, but the effect of abstinence was much greater in the asthenozoospermic group than in the oligozoospermic group (14% compared with 1.4% of the within subject variation). Significant changes in results accompanied repeated testing, notably rises in sperm concentration and motility. Sperm motility was lower in winter and higher in summer in both groups and also, but to a lesser extent, in artificial insemination donors who collected semen in the laboratory. CONCLUSIONS duration of abstinence, the elapse of time and seasonal temperature changes affect semen analysis results, and therefore controls for these variables must be incorporated in any therapeutic trial for male infertility. On the other hand, they only account for a small proportion of the total variability and thus routine correction of results would not greatly improve the value of semen analysis in the prediction of fertility. Furthermore because differences in the duration of abstinence have only a small effect on sperm concentration in oligozoospermic men, restricting sexual intercourse to the time of ovulation may not enhance fertility.

Palliative operative management in rectal carcinoma.

Abstract: The results of palliative operative management of 338 patients with rectal carcinoma managed by one of the authors are presented Postoperative mortality was higher for patients undergoing palliative resection (117 per cent) than colostomy bypass (53 per cent) or diagnostic laparotomy (68 per cent) Cancer specific survival following palliative resection was significantly (P less than 0001) longer than that following colostomy bypass or diagnostic laparotomy for tumor Stages D1 (local visceral involvement) and D2 (distant metastases) However, in patients with liver or peritoneal metastases alone, cancer specific survival did not differ significantly after the operations of resection or colostomy bypass The failure to demonstrate improved survival after resection of the primary tumor in these latter two groups with distant metastases indicates the dominant role of volume of tumor tissue present in these situations The results suggest that longer survival following palliative resection reflects a bias of patient selection towards more favorable cases

Factors affecting an anaesthetist's work: some findings on vigilance and performance.

Abstract: This paper reviews factors which may influence the vigilance tasks of an anaesthetist during an anaesthetic. Vigilance tasks are found to be unlike any other automatic, repetitive or monotonous tasks. While many factors affect vigilance and may result in performance decrements during psychological testing, little of this work has been done on anaesthetists. We suggest, however, that there are many parallels between findings related to vigilance in general and the type of work done by anaesthetists. Implications of major factors are discussed, and recommendations for further study are proposed. Language: en

A note on audit report readability

Abstract: Effective communication of the information contained in audit reports depends on how easily the general user of such reports can understand them. This study of audit reports indicates that many users of the reports have difficulty in understanding them.

A Small Sample Property of the Cliff-Ord Test for Spatial Correlation

Abstract: SUMMARY The Cliff-Ord test for spatial correlation in regression disturbances is found to be a locally CLIFF and ORD (1973) proposed a test for spatial correlation in regression disturbances. They informally argued that for values of the spatial correlation parameter, p, in the neighbourhood of zero, their test coincides with the likelihood ratio test derived assuming the value of p under the alternative hypothesis is known. Recently, Burridge (1980) demonstrated that the Cliff-Ord test is identical to the Lagrange multiplier test and is therefore asymptotically equivalent to the likelihood ratio test. In this note we examine some of the test's small sample power properties. It is found to be a Locally Best Invariant (LBI) test in the neighbourhood of p = 0, while for a special type of spatial correlation and when the regression has an intercept, it is a Uniformly Most Powerful Invariant (UMPI) test. Consider the usual linear regression model,

Resected ovarian recurrence from colorectal adenocarcinoma: a study of 13 cases.

Abstract: Thirteen (1.4 per cent) of 882 female patients managed by resection for primary colorectal adenocarcinoma subsequently required operation for ovarian recurrence. The clinical, pathologic and survival data of this group have been analyzed. Their age (mean±s.d., 51.2±8.4 years) was less (P=0.004) than that of the total series of female patients (59.4±13.0 years). Survival varied from 15 to 96 months (mean 17 months) from the ovarian operation. Three patients were still alive with no evidence of recurrence at the time of review. The low incidence of clinical ovarian recurrence requiring operation does not support recommendations for prophylactic oophorectomy in all patients.

Temporal changes in rat Leydig cell function after the induction of bilateral cryptorchidism

Abstract: Summary. Adult rats were made bilaterally cryptorchid and studied at intervals of 3, 7, 14 or 21 days to study temporal changes in Leydig cell function. Serum FSH and LH levels were measured and the cross-sectional area of the Leydig cells assessed by morphometry. The function of the Leydig cells was judged by the binding of 125I-labelled hCG to testicular tissue in vitro and the testosterone response of the testis to hCG stimulation in vitro. By 3 days after cryptorchidism, the binding of labelled hCG to testicular tissue was significantly decreased compared to that of controls, but the testes were able to respond to hCG stimulation in vitro. At 7, 14 and 21 days after cryptorchidism, an enhanced testosterone response was observed and the size of the Leydig cells was significantly greater than that of the controls, which indicated increased secretory activity by the cryptorchid testis. Although serum FSH levels were significantly elevated after 3 days of cryptorchidism, serum LH levels did not rise until 7 days, thereby suggesting that the loss of receptors is unlikely to result from down-regulation by LH. The reduced testosterone response of the cryptorchid testis in vivo to low doses of hCG and the enhanced response at high doses are probably related to the reduced blood flow to the cryptorchid testis and the decreased sensitivity of the Leydig cells induced by LH/hCG receptor loss.