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Methanococcus jannaschii accumulates alpha- and beta-glutamate as osmolytes. The effect of these and other solutes on the thermostability of two multisubunit metabolic enzymes from M. jannaschii, aspartate transcarbamoylase catalytic trimer (ATCase C3) and glutamine synthetase (GS), has been measured and compared to solute effects on bacterial mesophilic counterparts in order to explore if osmolytes accumulated by each organism can preferentially stabilize the proteins to thermal unfolding. For both ATCase enzymes and for the B. subtilis GS, the solutes normally accumulated by the organism were very effective in protecting the enzyme from losing activity at high temperatures, although solute effects on loss of secondary structure did not necessarily correlate with this thermoprotection of activity. The recombinant M. jannaschii GS exhibited quite different behavior. The pure enzyme had a thermal unfolding transition with a midpoint temperature (Tm) less than 60 degrees C, well under the growth temperature of the organism (85 degrees C). None of the small molecule solutes tested (including the K+-glutamate isomers accumulated by M. jannaschii) significantly stabilized the protein to incubation at 85 degrees C. Instead, protein-protein interactions, as illustrated by E. coli GroEL or ribosomal protein L2 stabilization of GS, appeared to be the dominant factor in stabilizing this archaeal enzyme at the growth temperature.

In the years 1999-2000, there was an increase in the incidence of meningococcal disease in Victoria, largely caused by Neisseria meningitidis serogroup C. This change was associated with a shift in age distribution of cases, with relatively more disease appearing in the 15-29 year age group, and with 40/58 serogroup C isolates in 2000 exhibiting a new macrorestriction pattern (pattern A). Thirty-four of 52 pattern A isolates tested displayed the novel phenotype C:2a:P1.4, and were consistently porA VR type P1.7-2,4 by DNA sequencing. Nine of 10 representative pattern A isolates analysed displayed a housekeeping gene allele profile (ST-11) that is characteristic of the electrophoretic type (ET)-15 variant that has caused outbreaks in Canada, the Czech Republic and Greece. Meningococci belonging to the ST-11 complex that were isolated in Victoria prior to 1999 did not display either restriction pattern A or PorA VR type P1.7-2,4.

Methanococcus thermolithotrophicus, a thermophilic methanogenic archaeon, produces and accumulates beta-glutamate and L-alpha-glutamate as osmolytes when grown in media with <1 M NaCl. When the organism is adapted to grow in >1 M NaCl, a new zwitterionic solute, N(epsilon)-acetyl-beta-lysine, is synthesized and becomes the dominant osmolyte. Several techniques, including in vivo and in vitro NMR spectroscopy, HPLC analyses of ethanol extracts, and potassium atomic absorption, have been used to monitor the immediate response of M. thermolithotrophicus to osmotic stress. There is a temporal hierarchy in the response of intracellular osmolytes. Changes in intracellular K(+) occur within the first few minutes of altering the external NaCl. Upon hypoosmotic shock, K(+) is released from the cell; relatively small changes occur in the organic osmolyte pool on a longer time scale. Upon hyperosmotic shock, M. thermolithotrophicus immediately internalizes K(+), far more than would be needed stoichiometrically to balance the new salt concentration. This is followed by a decrease to a new K(+) concentration (over 10-15 min), at which point synthesis and accumulation of primarily L-alpha-glutamate occur. Once growth of the M. thermolithotrophicus culture begins, typically 30-100 min after the hyperosmotic shock, the intracellular levels of organic anions decrease and the zwitterion (N(epsilon)-acetyl-beta-lysine) begins to represent a larger fraction of the intracellular pool. The observation that N(epsilon)-acetyl-beta-lysine accumulation occurs in osmoadapted cells but not immediately after osmotic shock is consistent with the hypothesis that lysine 2,3-aminomutase, an enzyme involved in N(epsilon)-acetyl-beta-lysine synthesis, is either not present at high levels or has low activity in cells grown and adapted to lower NaCl. That lysine aminomutase specific activity is 8-fold lower in protein extracts from cells adapted to low NaCl compared to those adapted to 1.4 M NaCl supports this hypothesis.

The structure of the crown ether 1,8-(3,6,9-trioxaundecane-1,11-diyldioxy)-9,10-dihydro-10,10-dimethylanthracene-9-ol, C(24)H(30)O(6).H(2)O (1), code name P326, the parent compound for a series of derivatives, has been determined by both X-ray diffraction at room temperature and neutron diffraction at very low temperature. The unit cells are very similar at both temperatures and in both cases the crystals exhibit P2(1) symmetry with Z = 4 (two molecules, A and B, respectively, per asymmetric unit) and pseudosymmetry P2(1)/c. The higher symmetry is broken mainly by the two independent water molecules in the unit cell, some reflections which would be absent in P2(1)/c having strong intensities in both the X-ray and neutron data. In both molecules A and B hydrogen bonds involving the water molecule stabilize the macrocyclic ring structure, one involving the macrocyclic O(9) as a donor. Close contacts between the water and macrocyclic O atoms in each molecule also suggest the presence of two bifurcated hydrogen bonds, involving water HW2 to both O(16) and O(18), and water HW1 to both O(18) and O(20), respectively, with considerable variation in the geometry being present. Both molecules A and B exhibit very close pseudosymmetry across a plane perpendicular to the molecular plane and through atoms C(9) and O(18), and in addition are predominantly planar structures. The X-ray analysis failed to reveal one H atom per water molecule, each being subsequently included after location and refinement in the neutron analysis.

The halophilic methanogen Methanohalophilus portucalensis synthesizes three distinct zwitterions, (beta)-glutamine, N(sup(epsilon))-acetyl-(beta)-lysine (NA(beta)Lys), and glycine betaine, as osmolytes when it is grown at high concentrations of external NaCl. The selective distribution of these three species was determined by growing cells in the presence of osmolyte biosynthetic precursors. Glycine betaine is formed by the stepwise methylation of glycine. Exogenous glycine (10 mM) and sarcosine (10 mM), although internalized, do not bias the cells to accumulate any more betaine. However, exogenous N,N-dimethylglycine (10 mM) is available to the appropriate methyltransferase and the betaine generated from it suppresses the synthesis of other osmolytes. Precursors of the two zwitterionic (beta)-amino acids ((beta)-glutamate for (beta)-glutamine and (alpha)-lysine and diaminopimelate for NA(beta)Lys) have only small effects on (beta)-amino acid accumulation. The largest effect is provided by L-(alpha)-glutamine, suggesting that nitrogen assimilation is a key factor in osmolyte distribution.

During a prolonged outbreak of meningococcal disease caused by serogroup B serotype 15 sulphonamide-resistant strains in one British health district, there was considerable variation in attack rates by town. General practitioner (GP) antibiotic prescribing rates were compared in high and low incidence towns. The only significant difference found was that erythromycin prescribing was more frequent in the high incidence towns (rate ratio 4.0, 95% CI 3.2-4.8, in March 1987 and 3.0, 95% CI 2.4-3.7, in November 1987). This was probably due to increased GP consultation rates for upper respiratory tract infection (URTI), but higher erythromycin usage may have increased meningococcal acquisition rates or susceptibility to meningococcal disease. Antibiotic prescribing rates should be further investigated in defined areas of high and low incidence of meningococcal disease.

Continuously grown cells from a glucose limited chemostat were flocculated with four different cationic polymers. The polymer was added to the cells either dropwise or as a slug at the start of the flocculation period. Dose curves for each polymer type and using each method of polymer addition were constructed. It was evident that classical overdose was possible with all four polymers if slug addition was used. Continuous addition produced dose curves overdose was possible with all four polymers if slug addition was used. Continuous addition produced dose curves with no overdosing except when low molecular weight, low charge density polymer was used. The dose curves could be combined if they were based on amount of charge added. The dose curve was not linear, but fitted a logarithmic model well. Charge density was much more important than MW of the polymer.

Objective: To determine the prevalence and clonality of non-toxigenic Corynebacterium diphtheriae biovar gravis in a community with two cases of endocarditis caused by this organism., Setting: A Koorie (Aboriginal) community in Gippsland, eastern Victoria, in 1994., Methods: Nose and throat swabs were collected from 359 community contacts of the cases and cultured for C. diphtheriae. Strains isolated from the contacts were compared by pulsed-field gel electrophoresis (after digestion with Sma1, Not1 and Sfi1) with those from the invasive cases in the same community, another invasive case in Victoria, a cluster of invasive cases in New South Wales (NSW) (1990-1991), and other stored strains isolated from skin ulcers and sore throats., Results: Non-toxigenic strains of C. diphtheriae biovar gravis were isolated from throat swabs of five of the case contacts. Uniform DNA patterns were found for the two community cases, the other Victorian case, nine of ten isolates from NSW, and the five throat isolates from case contacts., Conclusion: An invasive clone of C. diphtheriae biovar gravis appears to have been responsible for the three Victorian cases of endocarditis. It was also present among case contacts and responsible for previous invasive cases in NSW. Prophylactic treatment should be considered for clearly defined contacts in all instances where C. diphtheriae is isolated from a normally sterile site, regardless of the toxigenic nature of the strain.

The authors noticed a marked increase in the incidence of reactionary post-operative haemorrhage after tonsillectomy during the course of 1992. This increase appeared to be related to the introduction of diclofenac as a post-operative analgesic. A retrospective review of casenotes of patients having tonsillectomy under the care of the senior author (P.M.R.) in 1992 revealed that four of the 73 patients (5.5%) receiving diclofenac at induction of anaesthesia suffered reactionary haemorrhage requiring operative control, as compared with two of 293 (0.7%) receiving other analgesics.

Objective: To determine if HPV detection or the size of a tampon specimen is affected by the menstrual cycle., Materials: Two hundred and eighty women between 18-35 years of age attending a gynaecology clinic at The Royal Women's Hospital were enrolled. Each woman completed a questionnaire on the risk factors of HPV infection and provided a tampon specimen. Specimens were analysed for the presence of HPV DNA (polymerase chain reaction with the L1 consensus primers) after the pellet volume and number of cells was assessed., Results: The mean age of the 298 women enrolled in this study was 27.0 years (SD 4.5, range 18-35). Ninety two (30.9%) of the tampon specimens were positive for HPV using the L1 consensus primer. The detection of HPV DNA was not associated with the quartiles of the menstrual cycle (p = 0.32). Both the pellet volume and the number of cells from a tampon specimen were greater during the mid cycle, although this was significant for the pellet volume only (p = 0.002 and 0.1 respectively). The pellet volume was not significantly associated with other variables assessed by the questionnaire. The number of cells from a tampon specimen increased with the numbers of life time sexual partners (p = 0.02) and was higher for a single marital status (p = 0.0008)., Conclusion: The timing of the menstrual cycle effects the size of tampon specimens but not the probability of detecting HPV DNA.

Fourteen-day fetal mouse colon was transplanted under the kidney capsule of an adult mouse to determine whether this system could be used as a model of embryonic colonic development. The 14-day fetal colon was transplanted and left for a period of 7 days. Comparisons of the normal one day postnatal colon and the transplanted colon were made morphologically and morphometrically. It was found that the transplanted fetal colon resembled its postnatal counterpart with respect to morphology; the cell types seen in the transplanted colon were similar to those observed in the in situ colon of the same age. However, morphometric analysis showed that the transplanted colon was significantly smaller than its postnatal counterpart, suggesting that conditions in the host were not optimal to support the full growth of the colon. In spite of this, it appears that the fetal colon can differentiate normally under the kidney capsule and this model can be used to study both epithelial-mesenchymal interactions and the role of hormones in fetal colonic development.

In order to determine whether cortisol acts directly at the level of the fetal pituitary to promote pars distalis corticotroph maturation, we have infused cortisol into the hypothalamo-pituitary-disconnected (HPD) fetal sheep from 111 to 117 days of gestation. In this study we have measured fetal plasma cortisol and immunoreactive adrenocorticotrophic hormone (ir-ACTH) concentrations between 105 and 116 days of gestation, and we have determined the proportions of adult- and fetal-type corticotrophs in the pars distalis of catheter control fetuses and in HPD fetuses infused with either saline (HPD+SAL) or cortisol (2 mg/day; HPD+F). The fetal plasma cortisol concentrations did not change significantly following HPD. The mean fetal plasma cortisol concentration between 113 and 116 days was threefold higher in the HPD+F fetuses than that measured in HPD fetuses. Following HPD, fetal plasma ir-ACTH concentrations were significantly higher than in catheter control fetuses. Despite the significant elevation in plasma cortisol concentrations in HPD+F fetuses between 113 and 116 days, plasma ir-ACTH concentrations were not different in these fetuses from HPD fetuses infused with saline. At 117 days of gestation in HPD+F fetuses, the proportion of fetal-type corticotrophs in the pars distalis was significantly less than in the HPD+SAL fetuses; however, there was no significant change in the proportion of adult-type corticotrophs in the pars distalis following cortisol infusion. We have shown that cortisol has a direct trophic effect on the maturation of the pars distalis corticotrophs; however, the full maturation of these cells requires an intact hypothalamo-pituitary axis. These findings demonstrate the importance of the fetal hypothalamus in anterior pituitary corticotroph maturation during the last third of gestation.

It is unclear whether the maturation of corticotrophs from the fetal to the adult type in the fetal sheep pituitary in late gestation is associated with changes in the sensitivity of the fetal pituitary to corticotrophic secretagogues and in the form of ACTH-containing peptides (IR-ACTH) secreted into the circulation. The maturation of the pituitary corticotroph population is known to be accelerated by intrafetal cortisol infusion and delayed by bilateral fetal adrenalectomy. We have therefore investigated the mol wt profile of IR-ACTH present in fetal sheep plasma from 110 days gestation until term (147 +/- 3 days) and determined whether intrafetal cortisol infusion between 105-117 days (2.5 mg cortisol/day), or bilateral fetal adrenalectomy can alter the mol wt profile of IR-ACTH in fetal sheep plasma. We have also investigated whether prior exposure to cortisol alters the subsequent responsiveness of the fetal pituitary to a long term infusion of ovine (o) CRF (10 micrograms oCRF/day). In the control group, the proportion of IR-ACTH which eluted in the low-mol wt (LMW) range (i.e. less than 12K) was significantly higher between 121-125 days (43.9 +/- 4.2%) than between 126-139 days (26.8 +/- 9.3%) but not different to that after 140 days gestation (29.9 +/- 5.5%). Between 110-117 days, cortisol infusion had no effect on the proportion of IR-ACTH in the LMW range (43.9 +/- 5.7%, saline infused; 44.1 +/- 2.4%, cortisol infused). Between 121-125 days, the proportion of IR-ACTH in the LMW range in the CRF-infused groups (with or without prior exposure to cortisol) was significantly lower (27.4 +/- 2.1%) than in the saline-infused control group. In contrast, after fetal adrenalectomy, the proportion of IR-ACTH in the LMW range between 126-139 days was significantly higher (48.0 +/- 6.7%) than in intact control animals (23.8 +/- 3.5%). We conclude that the change in the mol wt profile of IR-ACTH in fetal plasma after 125 days may be a consequence of changes in the morphological and/or functional characteristics of the corticotrophic cells in the fetal pituitary. Infusion of oCRF appears to accelerate the normal maturation of the fetal pituitary-adrenal relationship, and oCRF acting either directly or via secretion of cortisol may play a role in the posttranslational processing of POMC in the fetal sheep pituitary after 125 days gestation.

We have investigated the effect of hypothalamo-pituitary disconnection (HPD) on the maturation of basal ir-ACTH and cortisol concentrations in fetal sheep plasma, and on the development of the anterior pituitary corticotroph population in the last third of gestation. After HPD, fetal plasma ir-ACTH concentrations were significantly elevated, and continued to rise with increasing gestational age. However, despite elevated ir-ACTH concentrations, there was no increase in fetal plasma cortisol concentrations, and parturition was delayed for at least 8 days beyond normal term. Furthermore, HPD resulted in a significant disruption of the maturation of the pars distalis corticotrophs. We also examined the change in fetal plasma concentrations of ir-ACTH and cortisol to exogenous CRF after HPD. There was a significant increase in plasma ir-ACTH in response to CRF administration in the HPD fetuses, which was qualitatively similar to that observed in sham-operated fetuses. In contrast, the plasma cortisol response was less in HPD fetuses when compared to that in sham-operated fetuses. The results of this study demonstrate that ir-ACTH secretion is not maintained by the fetal hypothalamus in the last third of gestation, and that ir-ACTH secretion is tonically inhibited by the hypothalamus during this time. The disconnection of the pituitary from the hypothalamus disrupts the maturation of the pituitary-adrenal axis, thus demonstrating the fundamental importance of the hypothalamo-pituitary axis in the normal maturational cascade which culminates in birth in this species.

Patients undergoing 204 endoscopic laryngeal operations were studied prospectively to determine the incidence of complications. Twelve patients were considered to be at high risk of postoperative airway obstruction. Two of these patients had an elective tracheostomy. One required temporary reintubation in the recovery room. No case of respiratory obstruction occurred in a patient not considered to be in the high risk group. Mucosal haemorrhage or oedema was seen on postoperative indirect laryngoscopy in 31 per cent of patients. The commonest abnormality found was mucosal haemorrhage in the oropharynx.

Oto-acoustic responses were observed in normal ears in the presence of a static pressure applied to the external canal. The influence of pressure on the amplitude and spectral composition of the response is described.

Between 1 October 1986 and 31 March 1987, 55 cases of meningococcal disease were identified in the South-West of England, an attack rate of 1.54 per 100,000 during the study period. Antibiotics used in the treatment of the disease successfully eliminated nasopharyngeal carriage of meningococci in 13 out of 14 cases without use of rifampicin. The overall meningococcal carriage rate in 384 close contacts was 18.2% and the carriage rate of strains indistinguishable from the associated case strain was 11.1%. The carriage rate of indistinguishable strains in household contacts (16.0%) was higher than the carriage rate in contacts living at other addresses (7.0%, P less than 0.05). A 2-day course of rifampicin successfully eradicated meningococci from 46 (98%) of 47 colonized contacts. In one third of cases groupable meningococci were isolated from at least one household contact; 92% of these isolates were of the same serogroup as the associated case strain. When a meningococcus is not isolated from a deep site in a clinical case of meningococcal disease, culture of serogroup A or C strains from nasopharyngeal swabs of the case or of household contacts is an indication that the close contact group should be offered meningococcal A + C vaccine in addition to chemoprophylaxis. The failure in this and other studies to isolate meningococci from any household contact in the majority of cases may be due either to the relative insensitivity of nasopharyngeal swabbing in detecting meningococcal carriage or to the acquisition of meningococci by most index cases from sources outside the household.

In this study we have applied the technique of hypothalamo-pituitary disconnection (HPD) to the fetal sheep at 108-112 days of gestation. The pituitary is surgically disconnected from the hypothalamus by the removal of the neural component of the median eminence above the level of the portal circulation. This procedure results in the complete disconnection of the pituitary from the hypothalamus. After HPD, the lactotroph response to the dopamine antagonist chlorpromazine was significantly reduced (p less than 0.005) indicating the functional isolation of the pituitary gland from the hypothalamus. The increase in plasma prolactin in response to exogenous thyrotrophin-releasing factor was maintained following HPD. HPD resulted in the complete atrophy of the pars nervosa. At 132-135 days of gestation after HPD there was no change in the volume or appearance of the pars distalis; small infarcts were observed in the pars distalis of some HPD fetuses, but these occupied less than 1% of the volume of the anterior lobe of the pituitary. There was a significant increase (p less than 0.05) in the volume of the pars intermedia after HPD. Gestation was prolonged for at least 8 days beyond normal term following HPD, indicating that the processes integral to the initiation of parturition at term had been disrupted. We conclude that HPD provides a good in vivo model for the investigation of the activity of the isolated pituitary gland, and for the examination of the role of neuroendocrine mechanisms in fetal sheep development in the latter third of gestation.

Aspects of the cell kinetics of the developing intestinal epithelium of fetal sheep were investigated by autoradiography. The sites of (3H)-thymidine uptake were localized in the small intestinal epithelium of fetal sheep from 60 to 145 days' gestation. Labeled cells were always confined to the intervillus progenitive zone, either between the bases of adjacent villi in the younger fetuses or in crypts. There were no labeled cells within the villus epithelium. Labeled and unlabeled cells within the progenitive zones were counted in proximal and distal regions of the small intestine. The proportion of cells labeled (PCL) was unaffected by the route of administration of (3H)-thymidine into the fetus. There was no clear age-related trend in PCL of the distal region (mean distal PCL, 0.23 +/- 0.03). On the other hand, in proximal regions, PCL was at its highest value at 60 days (0.33), falling to a minimum of 0.14 at 130 days, before rising to 0.25 (+/- 0.04) at 136 days. These results demonstrate that the proliferation of enterocytes in utero is qualitatively similar to that in the adult, being confined to a distinct progenitive zone. Such a finding is an important first step in understanding changes in enterocyte structure and function, since this may, as seen in the adult, be largely determined by the rates of division and renewal.

At 90 days gestation a uniquely fetal-type and an adult-type corticotroph have been observed in the fetal sheep pars distalis (term approximately 147 days). Between 90 and 130 days gestation the fetal type is predominant, and its numbers decline toward term. In this study the effect of the endogenous cortisol surge on the change in the population of corticotrophs in the pars distalis was investigated in sheep fetuses after bilateral adrenalectomy at 120 days gestation or after an infusion of 2 mg cortisol/day between 109 and 115 days gestation. The total proportion of corticotrophs, expressed as a percentage, decreased significantly (P less than 0.01) from 115 days in saline-infused controls (21.09 +/- 1.10%) and 135 days in intact controls (14.59 +/- 1.12%). The percentage of adult-type corticotrophs increased significantly (P less than 0.01) from 5.65 +/- 0.77 at 115 days, to 11.93 +/- 1.41 at 135 days. The percentage of fetal-type corticotrophs decreased significantly (P less than 0.001) from 14.91 +/- 0.35 at 115 days to 2.33 +/- 0.48 at 135 days. A small proportion of ACTH-immunoreactive cells could not be defined as either adult- or fetal-type corticotrophs. These changes in the corticotroph population had not occurred at 135 days in fetuses that had been adrenalectomized at 120 days; the percentage of corticotrophs relative to unstained cells (21.70 +/- 0.46%), the percentage of adult-type corticotrophs (6.42 +/- 0.29%), and the percentage of fetal-type corticotrophs (14.65 +/- 0.49%) were similar to those in 115-day-old fetuses, indicating that the normal change in the corticotroph population between 115 and 135 days gestation was dependent upon the presence of the fetal adrenal. In fetuses exposed to exogenous cortisol between 109 and 115 days gestation, the percentage of corticotrophs relative to unstained cells (16.53 +/- 1.68%), the percentage of adult-type corticotrophs (12.40 +/- 1.34%), and the percentage of fetal-type corticotrophs (3.78 +/- 0.58%) were similar to those at 135 days. This indicates that a short period of increased fetal plasma cortisol can bring about premature maturation of the corticotrophs in the fetal sheep pars distalis. We have also described an ACTH-immunoreactive cell which has characteristics of both an adult- and a fetal-type corticotroph. Its morphological appearance suggests that it may be a transitional stage from the fetal- to the adult-type corticotroph.(ABSTRACT TRUNCATED AT 400 WORDS)

Suppression of salivary flow is of value in the management of salivary fistulae and sialectasia. It may also be beneficial in mentally defective patients and those with neurological palsies lacking control of their salivation. Nine patients were treated by irradiation to the parotid gland to control salivary flow; eight had complete resolution of symptoms and one had partial relief. Irradiation was effective as primary treatment and after failed surgery and/or drug treatment. Low doses were effective and there were no significant acute or long-term side effects. Its use avoids long-term medication and their potential side effects and may reduce the need for surgery.

The relationship between lung liquid flow and fetal lung development has been studied at the cellular level using ultrastructural techniques. Continuous in utero tracheal ligation and drainage (over a period of 21-28 days) both result in malformations of the developing fetal lamb lung. Ligated lungs are larger, and drained lungs are smaller, than normal lungs at a similar gestational age. These changes are not merely due to altered lung liquid volume, but actual tissue growth thas been affected. Future alveolar wall thinning is enhanced in ligated lungs and inhibited in drained lungs, whilst the presence of differentiated alveolar type II cells (probably related to surfactant production) is decreased in ligated lungs and markedly enhanced in drained lungs. These results indicate the importance of fetal lung liquid in the regulation of pulmonary development in the fetus.

The determination of partial genotype, B/b and D/d, for coat colour in dogs, from phenotypic observations, is discussed. It is shown that the probability of a given genotype can be reliably determined where multiple observations on the mating of a given dog are available.

The goitrogen methylthiouracil was administered orally to pregnant ewes of known gestational ages to induce hypothyroidism in both mother and fetus. Developing pituitary thyrotrophic cells were studied using electron microscopy to detect the earliest gestational age at which morphological changes occurred in response to lowered plasma thyroid hormone concentrations. At 50 days of gestation, the pituitaries of fetuses exposed to the goitrogen were indistinguishable from untreated control glands. However, at 58 days and subsequent ages, "thyroidectomy' cells were observed in pituitaries of all hypothyroid fetuses. These findings indicate that fetal sheep pituitary thyrotrophs are sensitive to lowered thyroid hormone concentrations by 58 days of gestation, suggesting that thyroid-thyrotroph interaction exists at this early stage of development.

We have investigated the role of gastrin in the development of the gastrointestinal tract during the latter part of gestation in fetal sheep. We surgically removed the major source of gastrin, the gastric (abomasal) antrum, from five fetuses at 90 days of gestation. The remaining abomasum was anastomosed to the pylorus allowing unobstructed flow of luminal contents. Another five fetuses, subjected to sham-antrectomies at 90 days, served as controls. Further surgery was performed in all fetuses at 120 days for the placement of vascular catheters to permit measurement of plasma gastrin concentrations. The fetuses were infused with [3H]thymidine to study villus cell migration rates. At 135 days of gestation samples of gastric (abomasal) fundus, and proximal and distal small intestine, were processed for histology and morphometric analysis. The antrectomized fetuses had significantly lowered plasma gastrin concentrations (P less than 0.025) between 120 and 135 days. At 135 days, the mean body weight, crown-rump length, total gut weight and small intestinal weight and length were not significantly different between the two groups. Similarly, there were no significant differences between groups in the mean thicknesses of the gut wall, mucosa and muscularis externa, or in the mean villus height and crypt depth in the proximal or distal parts of the small intestine. Villus cell migration rate in the proximal and distal small intestine was not affected by antrectomy. No simple relationship could be demonstrated between any of these parameters and plasma gastrin concentration. In the antrectomized fetuses, the mean crypt density and crypt-to-villus ratio were significantly reduced in the proximal small intestine (P less than 0.05), while only the density of villi was reduced in the distal small intestine (P less than 0.05). In the antrectomized fetuses there were significant correlations between plasma gastrin and the fraction of fundic mucosa occupied by gland and pit (P less than 0.005), and between plasma gastrin concentration and villus density (P less than 0.01) and crypt-to-villus ratio (P less than 0.025) in the proximal small intestine. In the sham group these correlations were absent. We conclude that the removal of the gastric antrum in fetal sheep results in decreased plasma gastrin concentration, and that gastrin appears to have a regulatory or trophic role on the gut mucosa in these circumstances.(ABSTRACT TRUNCATED AT 400 WORDS)

Fetal or newborn rat and guinea-pig sympathetic ganglia were cultured in Rose chambers. After periods of up to 14 days in vitro, cultures were processed for catecholamine fluorescence or acetylcholinesterase histochemistry. The two types of neuron previously identified showed different histochemical reactions. The less frequent, smaller Type I cells contained catecholamine but did not stain for acetylcholinesterase. These cells may be immature. The more common Type II cells showed reactions for both catecholamine and acetylcholinesterase and in this respect resembled mature ganglion cells.

The relationship between fetal espiratory activity and fetal lung development has been studied at the cellular level using two experimental models. Chronic bilateral phrenectomy over a period of 20-28 days during the last trimester of the fetal lamb resulted in hypoplastic lungs, although cellular maturity, as indicated by the presence of alveolar epithelial Type II cells, was present. In the lungs from fetal lambs undergoing sham operations for a similar time course there was evidence of enhanced alveolar proliferation when compared with lungs from normal fetal sheep of a similar gastational age, most probably as a result of operative stress. Following chronic bilateral vagotomy no changes in size or histology of the fetal lamb lungs were detected. At an ultrastructural level, however, inclusions of Type II cells consistently showed the loss of the typical osmiophilic lamellated appearance. These results indicate the importance of the fetal breathing apparatus in maintaining a volume of lung liquid which is adequate for normal pulmonary development, particularly during the phase in which alveoli are formed.

Using light and electron microscopy, the morphogenesis of the pars intermedia of the sheep pituitary gland was examined in developing lambs between 26 days of gestation and the newborn stage. Following the establishment of contact between the anterior and posterior lobe primordia seen at 26 days, the connection with the pharyngeal roof disappeared by 31 days. The lumen of Rathke's pouch, which was a prominent cavity at the earlier stages, became inconspicuous by 40 days but progressively increased in size during gestation and, in some newborn animals, contained colloid material. At 40 days the pars intermedia consisted of a uniform population of undifferentiated cells. Cells with cytoplasmic granules were first identified at 50 days. The cytological appearance of granular cells at 70 days indicated increased synthetic activity and by 80 days they closely resembled adult glandular cells. At 100 days, membrane activity suggestive of exocytosis was first observed in granular cells; fenestrated capillaries were present, and early follicle formation between adjacent non-granular cells was seen. This apparent exocytotic release of granules was observed much more frequently between 100 days of gestation and the newborn stage than in adult pars intermedia cells. These findings indicate that glandular cells of the developing pars intermedia are actively engaged in synthesis, storage and secretion from an early stage.

The migration of enterocytes was studied in the small intestine of foetal sheep at 115 and 136 days of gestation in utero. The speed of migration in all cases was slower than that reported in the adult. At 115 days, the migration rate was 4.88 and 4.96 percent villus height/day for the proximal and distal small intestine, respectively. At 136 days, the migration rate was significantly increased (p less than 0.05) to 12.0 for the proximal and to 8.5%, for the distal small intestine. Rates of villus length increase were between 0.007 and 0.012 mm/day over the time course studied. The migration rates, expressed as millimeters per day, were between 0.23 and 0.76 mm/day, hence the rate of migration was much greater (between 3 and 16 times) than the villus growth rate.

The frequency of B chromosomes has been determined for several stages in the grasshopper life-cycle, over three generations, in three natural populations spanning a steep cline in East Anglia. This has revealed a rise in B frequency in prediapause eggs, a fall during the winter in the embryos and a rise in the early nymphs in certain situations. The causes of these effects are discussed and also their importance, along with meiotic drive, in maintaining an environmentally correlated cline of stable adult B frequencies.

The effect of ACTH administration for 1-5 days on the morphology and steroidogenic capability of sheep adrenal tissue has been examined. During this period of treatment there was a gradual decline in the in vitro conversion of 3H-labelled precursors to products of solely zona glomerulosa origin (aldosterone and 18-hydroxycorticosterone) while conversion to products of zona fasciculata origin (17-hydroxyprogesterone, 11-deoxycortisol and cortisol) was stimulated throughout. Conversion to DOC, 18-hydroxydeoxycorticosterone and corticosterone (steroids produced by both the zona glomerulosa and the zona fasciculata) declined after initial stimulation. Within 2--3 days of the commencement of treatment, the zona glomerulosa showed a progressive decrease in cell number associated with disruption of cords and cell separation. Ultrastructurally, it was found that typical zona glomerulosa cells had almost disappeared. The majority of residual cells in this area had a structure intermediate between zona glomerulosa and zona fasciculata cells. The similarity in time-course of the alterations in both the morphological and biosynthetic characteristics suggests that the decline in aldosterone output caused by ACTH administration to sheep results from the loss of adrenal zona glomerulosa cells, predominantly due to selective cellular degeneration.

An immunocytochemical staining technique was used to localize four fragments [pro gamma MSH, gamma MSH, ACTH and beta endorphin/beta lipotrophin (beta endorphin/beta LPH)] of the proopiomelanocortin molecule in both the adult and fetal sheep pituitary. In the adult sheep anterior pituitary each fragment was localized in cells that were darkly stained, stellate and widely distributed throughout the gland. The same cells, identified in three serial sections, stained with anti-pro gamma MSH, anti-ACTH and anti-beta endorphin/beta LPH. In the fetal sheep anterior pituitary all the proopiomelanocortin derived fragments were present at 38 days gestation. Between about 90 and 130 days of gestation both adult type proopiomelanocortin cells (small, stellate) and uniquely fetal cells (large, columnar) were present. Both adult-type and fetal proopiomelanocortin cells were identified in serial sections of the fetal anterior pituitary, stained with anti-pro gamma MSH, anti-ACTH and anti-beta endorphin/beta LPH. The adult intermediate lobe was immunoreactive with anti-pro gamma MSH and anti-beta endorphin/beta LPH but not with anti-gamma MSH or anti-ACTH. The fetal intermediate lobe was immunoreactive with all four antisera from 60 days gestation.

The effect of cortisol on small intestinal maturation was investigated in catheterized fetal sheep by infusing 2 mg cortisol/d between 105 and 115 d gestation (term ca. 147 d). This treatment resulted in a fivefold increase in plasma cortisol compared with catheterized control fetuses of the same age. There were no detectable changes in enterocyte morphology after the cortisol infusion; the size and density of most intestinal components were largely unaffected by the treatment. By contrast, the kinetics of the enterocyte population were significantly altered by the raised cortisol levels. The proportion of crypt cells labelled was significantly increased from 0.20 +/- 0.04 to 0.33 +/- 0.03 in the proximal region (P less than 0.01) and from 0.22 +/- 0.03 to 0.31 +/- 0.02 in the distal region (P less than 0.01). The migration of enterocytes in both regions was significantly increased to nearly twice the control values (P less than 0.05). Correspondingly, renewal time was almost halved in both regions, while cell density was unchanged in distal and decreased in proximal regions. Hence cell loss appeared to have increased as a result of the cortisol infusion. The kinetic parameters for the villus enterocyte population of the fetuses receiving cortisol before 115 d were of similar magnitude to those previously seen in the normal near-term fetus. To this extent exogenous cortisol treatment given before a pre-partum surge mimicked the action of the endogenous hormone in late gestation.

Eight cases of nasopharyngeal cyst are reviewed. Five were asymptomatic. Marsupialization of the cyst provided adequate treatment in the three symptomatic cases.

We have examined the influence of preventing the passage of swallowed fluid on the development of the small intestine during late gestation in fetal sheep. In four fetuses at 90 d of gestation, the oesophagus was ligated and fistulated, causing swallowed fluid to enter the amniotic sac. Tissue was removed from proximal and distal parts of the small intestine for histological analysis at 136 d (term is 147 d). The body weights of the four experimental fetuses were not significantly different from those of fourteen age- and breed-matched fetuses which were used as controls. However, the width of the mucosal layers at both sites in the small intestine was reduced by approximately 25% in the fistulated fetuses. This was largely attributable to a reduction in villus height of approximately 30%. The densities of villi and crypts increased significantly at the proximal and distal sites respectively. These findings indicate that the ingestion of fluid during late gestation plays a role in promoting growth of the mucosal elements of the small intestine. The way in which this occurs is not clear although it may be mediated either by trophic factors present in either amniotic or pulmonary fluid, or by the release of gastrointestinal hormones, such as gastrin, as a result of gut distension.

Although the small intestine of the sheep is relatively mature at birth, there are still vacuolated enterocytes present for at least 2 days in distal regions. In the distal regions, vacuolated cells possess a range of vesicle morphology which might be indicative of at least 2 separate routes for enterocyte handling of proteins taken up from the lumen. The localisation of immunoreactive immunoglobulins within the enterocytes, presumably of colostral or milk origin, in both proximal (non-vacuolated) and distal (vacuolated) regions, does not follow patterns which suggest orderly renewal at closure. It is suggested that closure is not solely brought about by epithelial cell replacement.

The effect of bilateral adrenalectomy at 120 d gestation on subsequent maturation of proximal and distal small intestine was investigated in chronically catheterized fetal sheep. Ten adrenalectomized and fourteen controls were examined at 136 d; some following infusion of [3H]thymidine at 3-6 d or 4 h before termination of pregnancy. Mean plasma cortisol levels were 5.3 +/- 0.7 ng/ml in the adrenalectomized group; control values ranged from 14 to 39 ng/ml level during the 2-week experimental period. Fetal body growth was significantly increased following adrenalectomy. In the small intestine, growth of mucosal structures was reduced, especially in distal regions. Villus height was significantly reduced in both regions. External muscle thickness was significantly increased in both regions. Despite these changes there was no alteration in villus enterocyte morphology, nor were there any significant changes in villus or crypt densities. The proportion of crypt cells labelled with [3H]thymidine was unaffected by adrenalectomy. In proximal regions, migration rate of labelled enterocytes declined from 12.0 to 5.83% villus height/d (P less than 0.025) after adrenalectomy; there was no change in migration rate in distal regions. The estimated renewal time was greater in both proximal and distal regions in adrenalectomized compared with control fetuses.

The effects of hypophysectomy on the cell population of the adrenal cortex has been examined with light and electron microscopy. The sensitivity of the adrenal cortical cells to exogenous ACTH in both normal and hypophysectomized fetuses has been investigated by comparing plasma cortisol concentrations with structural changes in the adrenal cortex. Hypophysectomy was carried out at about 100 d and the subsequent analysis was made at about 135 d on fetuses catheterized at least 6 d earlier. The zona fasciculata of intact fetuses contained about 25% mature and 75% immature cells at 130-136 d. After hypophysectomy this zone contained a uniform population of immature cells and no mature cells; there was a significant reduction in both adrenal weight and cortical thickness. The zona glomerulosa was unaffected by hypophysectomy. The infusion of Synacthen 0 . 25 mg/d I.V. for 48 h did not affect the zona glomerulosa but resulted in a 2-fold increase in the thickness of the zona fasciculata in hypophysectomized and intact fetuses. This cortical growth was due to both hypertrophy and hyperplasia. All the cells in the zona fasciculata were mature following Synacthen treatment in both groups. The most striking difference between the secretory response of the adrenal cortex to Synacthen in the two groups was found within 3-6 h of the onset of infusion. Within this period there was a significant increment in the plasma cortisol concentration in the intact fetuses while no response was observed in the hypophysectomized animals. After 12 h infusion by contrast, a steadily rising response was observed in both groups. There was a significant correlation between the final plasma cortisol concentration and both the adrenal weight and cortical thickness after 48 h treatment. The increased sensitivity of the adrenal cortex to exogenous ACTH as term approaches in the sheep is considered to be dependent upon the increasing proportion of mature zona fasciculata cells within the adrenal cortex.

Recent papers have shown a high degree of disagreement between observers in the assessment of physical signs. In order to determine the interobserver variation in assessment of the larynx, 63 patients were each examined by 2 ENT registrars. The examiners agreed on the assessment of the voice in 80% of cases, and on the indirect laryngoscopy appearance in 76%. These results compare favourably with those reported previously for other forms of clinical examination.

Using indirect immunohistochemistry and an antiserum raised against rat corticotrophin-releasing factor (CRF) we have outlined an asymmetric network of cells and varicose fibers in sheep adrenal cortex. This network was not associated with the larger splanchnic nerves, but was occasionally found in small bundles or with blood vessels; in most instances fibers were found weaving independently through cortical parenchyma. A plexus of fibers was found in the zona reticularis, with a few fibers ramifying into adjacent medulla. Uni or bipolar cells were found throughout the cortex, with the greatest frequency at the corticomedullary junction; a multipolar-type cell was also found in this area. Staining of varicose structures and most cells was abolished by incubation with excess rat CRF 1-41, but not by ovine CRF or a range of other peptides. Though the immunoreactive species has not as yet been identified, it may thus share homology with sequences present in rat but not ovine CRF.

To determine which factors were associated with recurrence of otitis media with effusion following grommet insertion, the casenotes of 323 children who had a total of 485 operations for grommet insertion were reviewed. The incidence of repeat surgery was higher in those aged between four and six years, in those having grommet insertion between the months of July and October and in those cases in which the grommet was extruded within six months. Recurrence was not related to sex of the patient, month of listing for surgery, adenoidectomy, tonsillectomy, length of time on the waiting list or past history of previous grommet insertion.

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 functional maturity of the gastrointestinal system is essential for the survival of the neonate. The effects of reducing placental size and the ensuing fetal growth retardation on the development of the small intestine (SI) of the sheep fetus were investigated. At 140 days of gestation (term is 147 days), fetal body weight, gastrointestinal weight (from the abomasum to the rectum, i.e., the gut), SI weight, and SI length in the growth-retarded fetuses (n = 6) were significantly reduced (p less than 0.05) when compared with age- and breed-matched control fetuses. The SI weight was disproportionately reduced as a fraction of the gut weight or SI length (p less than 0.01). The proximal SI showed marked reductions in the thickness of the wall, muscularis externa, mucosa, villus height, and crypt depth (p less than 0.003). Densities of villi and crypts were also reduced (p less than 0.02). The crypt-to-villus ratio was maintained. Glycogen was accumulated basally in the villus epithelial cells, and their nuclei were located apically. These characteristics are comparable to those of much younger fetuses. In the distal SI, interanimal variation was large; however, the mean thickness of the wall, the muscularis externa, the mucosa, and the villus height were all reduced (p less than 0.05). In this region, the density of villi and crypts, the pattern of glycogen accumulation, and the position of the nuclei did not markedly differ between growth-retarded and control fetuses. Villus cell density was increased (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)