Canadian visual standards in aviation.
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Aerospace Medicine↗
Biomedical subjects
J M Wallace
Publications and source records attributed to J M Wallace.
Bronchoalveolar lavage cell and lymphocyte phenotype profiles in healthy asbestos-exposed shipyard workers.
The cellular and lymphocyte phenotypic composition of bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) from 15 healthy, nonsmoking, asbestos-exposed shipyard workers (AEW) and 10 nonsmoking, age-matched unexposed workers (UEW) were compared. None of the AEW had clinical, radiographic, or physiologic evidence of asbestosis, but six had radiographic evidence of pleural plaques and/or thickening. The mean duration of asbestos exposure was 16.3 +/- 2.3 yr, and the mean period since exposure was 10.8 +/- 0.5 yr. All but three of the AEW and none of the UEW had asbestos bodies detected in the first 20 ml of BAL fluid recovered (0.1 to 35 asbestos bodies/ml). The AEW had a significantly higher mean percentage (19.1 +/- 2.8% versus 9.7 +/- 1.6%) and concentration (31.6 +/- 5.2 x 10(3) cells/ml versus 14.7 +/- 2.5 x 10(3) cells/ml) of BAL lymphocytes compared with that in the UEW, with an increased mean concentration of each phenotype measured. In PB, the mean lymphocyte concentration was also higher in the AEW than in the UEW (2.0 +/- 0.3 x 10(3) cells/ml versus 1.5 +/- 0.3 x 10(3) cells/ml), but the difference was not statistically significant, and there was no increase of any phenotype measured. BAL lymphocytosis did not correlate with exposure history or BAL asbestos body count, but was greater in AEW with pleural abnormality (30.1 +/- 2.9% versus 11.8 +/- 1.6%). BAL concentrations of CD-20, CD-3, and CD-4, but not of CD-8 cells were significantly increased compared with those in the AEW without pleural abnormality. Further longitudinal studies are needed to determine the prognostic significance of these findings.
Adult↗
Does inadequate luteal function limit the establishment of pregnancy in the early post-partum ewe?
In Exp. 1 the effect of lactation versus early weaning on luteal function was examined in seasonally anoestrous Finn Dorset ewes that were induced to ovulate at 21 (N = 14) or 35 (N = 14) days post partum by using a CIDR device and PMSG. Prolactin concentrations were significantly higher (P less than 0.001) in lactating compared with early weaned ewes throughout the study. The proportion of lactating ewes with inadequate luteal function (as assessed by daily progesterone concentrations) in the 21-day group was 0.43 (3 or 7) compared with 0.67 (4 of 6) for those weaned within 2 days after parturition. Corresponding values for the 35-day group were 0 (0 of 4) and 0.14 (1 of 7) respectively. There was no evidence of abnormal luteal function in standard ewes (N = 8) for which the interval from parturition was greater than 150 days. In Exp. 2 we examined whether pregnancy can be successfully established during the breeding season following transfer of embryos into lactating or early weaned ewes in the early post-partum period. Embryos were donated from Border Leicester x Scottish Blackface ewes for which the interval from previous parturition was greater than 150 days. These embryos were transferred synchronously on Day 5 after behavioural oestrus to recipient ewes with the same breeding history as the donors (standard ewes, N = 15) or to lactating or early weaned recipients that had been induced to ovulate on Day 21 (N = 16) or 35 (N = 24) post partum. In the 21-day group inadequate luteal function was observed in 2 of 7 (0.28) lactating and 4 of 9 (0.44) early weaned ewes compared with corresponding values of 1 of 13 (0.08) and 2 of 11 (0.18) in the 35-day post-partum group. Luteal function was normal in all standard ewes. The proportion of successful pregnancies in the standard ewes was 0.80 (12 of 15) compared with 0 in lactating and early weaned ewes in the 21-day group and 0.08 (1 of 13) and 0.36 (4 of 11) respectively in the 35-day group. The incidence of inadequate luteal function is therefore independent of the suckling stimulus and is higher in ewes induced to ovulate on Day 21 than Day 35 post partum during breeding and non-breeding seasons.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Successful pregnancies after transfer of embryos recovered from ewes induced to ovulate 24-29 days post partum.
After lambing in late November, oestrus and ovulation were induced by using a CIDR device and PMSG in early weaned (N = 13) or lactating (N = 14) Border Leicester x Scottish Blackface ewes between 23 and 29 days after parturition. Ewes were intrauterine inseminated under laparoscopic visualization 54-55 h after CIDR-device withdrawal and eggs recovered on Day 3 of the cycle. Ovum recovery and fertilization rates were higher in lactating than in early weaned ewes, with fertilization being achieved as early as 24 days post partum in both groups. Of the 7 early weaned and 11 lactating ewes yielding eggs, fertilization occurred in 4 and 7 ewes respectively. A total of 20 embryos were transferred to the normal uterine environment of 15 recipient ewes in which the interval from parturition was greater than 150 days. Pregnancies were successfully established in 9 recipient ewes, resulting in the birth of 10 viable lambs. Prolactin concentrations were significantly higher (P less than 0.001) in lactating than in early weaned ewes throughout the study. Nevertheless, normal luteal function (as assessed by daily progesterone concentrations) was exhibited by 12 of 14 lactating and 8 of 13 early weaned ewes. Two post-partum donors in which the corpora lutea completely failed to secrete progesterone yielded fertilized eggs which developed to term when transferred to a normal uterine environment. The results show that sheep oocytes can be fertilized using laparoscopic intrauterine insemination as early as 24 days after parturition and that the resulting embryos are viable when recovered on Day 3 after oestrus and transferred to a normal uterine environment.
Animals↗
Fertilization and ovum recovery rates in superovulated ewes following cervical insemination or laparoscopic intrauterine insemination at different times after progestagen withdrawal and in one or both uterine horns.
In Exp. 1, 40 ewes were used in a 2 x 2 factorial design to investigate the effects of intrauterine versus cervical insemination and superovulation using pig FSH or PMSG and GnRH on egg recovery and fertilization rate. Cervical inseminations were carried out at 48 and 60 h (N = 20 ewes) and intrauterine insemination at 52 h (N = 20 ewes) after progestagen pessary withdrawal. Eggs were recovered on Day 3 of the oestrous cycle. Ovulation, egg recovery and fertilization rates were independent of the type of superovulatory hormone used. Fertilization rate was high irrespective of insemination site but intrauterine insemination at 52 h was associated with a significant (P less than 0.01) decrease in egg recovery of over 40% compared with cervically inseminated ewes. In Exp. 2 ewes were inseminated at 36 (N = 5), 48 (N = 6) or 60 (N = 6) h after pessary withdrawal to determine the optimum intrauterine insemination time to maximize both fertilization rate and egg recovery. Egg recovery per ewe flushed was 23, 59 and 67% after intrauterine insemination at 36, 48 and 60 h respectively. Correspondingly, 0, 85 and 100% of the eggs recovered were fertilized. The results of Exps 1 and 2 suggest that when intrauterine insemination occurs before or during ovulation it interferes with oocyte collection by the fimbria. In Exp. 3 egg recovery and fertilization rates were determined after cervical insemination at 48 and 60 h (N = 8) or intrauterine insemination at 48 (N = 9) or 60 (N = 8) h after progestagen withdrawal. Ewes in the last two groups were subdivided and inseminated unilaterally or bilaterally. Egg recovery was high after cervical insemination (95%) but only 36% of these eggs were fertilized. Unilateral intrauterine insemination was as effective as bilateral in ensuring high fertilization rates (100 versus 97%). Intrauterine insemination at 48 h compared with 60 h resulted in a significantly lower (P less than 0.05) percentage of eggs recovered (42 versus 90% respectively). However, reducing the degree of interference by adopting unilateral rather than bilateral insemination did not alleviate the detrimental effects of the 48-h insemination time on egg recovery. From these results we advocate the adoption of intrauterine insemination at 60 h after progestagen withdrawal to maximize fertilization rate and egg recovery in superovulated ewes.
Animals↗
Pulmonary infection in human immunodeficiency disease: viral pulmonary infections.
Viral pneumonitides are among the known pulmonary complications of human immunodeficiency virus (HIV) infection. Cytomegalovirus (CMV) pneumonitis is the most frequently recognized viral infection involving the lung. Although CMV may occasionally be the sole pathogen found to be responsible for severe pneumonitis in patients with the acquired immunodeficiency syndrome (AIDS), in most cases, its role in causing pulmonary disease is less clear, primarily because of the propensity to infect with a variety of other copathogens. CMV pneumonitis has been difficult to diagnose during life, although techniques utilizing in situ DNA hybridization or monoclonal antibodies for detection of the virus may improve the diagnostic yield of less invasive procedures such as bronchoalveolar lavage. Pneumonitis due to herpes simplex virus, varicella-zoster, and respiratory syncytial virus have occasionally been reported in AIDS patients, and are of practical importance because of the availability of effective treatment. The role of influenza and adenoviruses in causing HIV-related pulmonary complications is unknown, but could be of importance during outbreaks of these infections. Finally, data from several studies now suggest that Epstein-Barr virus or HIV itself or both have a role in the pneumonitis. Further study in this area could provide information leading to more effective management of this common complication of childhood AIDS.
Acquired Immunodeficiency Syndrome↗
Mycobacterium avium complex infection in patients with the acquired immunodeficiency syndrome. A clinicopathologic study.
Despite the recognition of Mycobacterium avium complex (MAC) infection as a common complication of AIDS, the specific clinical features, significance, and need for treatment have been difficult to assess. We reviewed the clinical records and autopsy material of 68 patients dying with AIDS, 32 (47 percent) of whom had MAC isolated from autopsy tissue. All had postmortem evidence of systemic infection. Eleven (34 percent) had MAC isolated from lung tissue. Little, if any, local tissue inflammation and destruction were associated with MAC infection. Patients with autopsy evidence of MAC infection had a longer time interval from diagnosis of AIDS to death. The infection was detected antemortem in 14 (44 percent), blood culture being the most sensitive means (86 percent yield). Although recurrent fever was noted among both MAC infected and uninfected patients, weight loss greater than 20 lb, weakness, anorexia, abdominal pain, and diarrhea were more frequent among infected patients. Severe anemia, thrombocytopenia, lymphopenia, and reduced mean CD-4 percentages and CD-4/CD-8 ratios were associated with MAC infection. Of eight patients who had MAC cultured antemortem and received multidrug antituberculosis therapy, none responded clinically, and all but one had MAC isolated at autopsy. Because MAC is associated with significant discomfort and disability, development of more effective treatment regimens could be beneficial for some affected AIDS patients.
Acquired Immunodeficiency Syndrome↗
Changes in the secretion of LH pulses, FSH and prolactin during the preovulatory phase of the oestrous cycle of the ewe and the influence of treatment with bovine follicular fluid during the luteal phase.
It has previously been shown that treatment of ewes with bovine follicular fluid (bFF) throughout the luteal phase of the oestrous cycle lowers plasma levels of FSH but increases the frequency and amplitude of the pulses of LH. Under these conditions, ovarian follicles grow to a maximum diameter of 2.7 mm and have a reduced capacity to release oestradiol. We have examined the nature of the gonadotrophin signals controlling follicular development in the normally cycling ewe and have investigated the effects of previous exposure to bFF on these signals and the follicular responses to them. Control ewes (n = 7) were injected i.v. with 9 ml bovine serum and treated ewes were injected with 9 ml bFF, twice daily from days 1 to 10 of the luteal phase (day 0 = oestrus). The ewes were injected with prostaglandin analogue on day 11 of the cycle to induce luteolysis and the gonadotrophin patterns were studied in blood sampled from these animals every 10 min for up to 72 h during the subsequent follicular phase. Following luteolysis (and the end of bFF treatment), LH pulse frequency increased rapidly in both groups and reached 1 pulse/h within 6 h. Thereafter, pulse frequency increased marginally and reached 1 pulse/50 min by the onset of the LH surge. This pattern was not affected by previous treatment with bFF. In the control ewes, the amplitude of the LH pulses did not change significantly following luteolysis or at any time during the follicular phase, while the levels of FSH declined slowly until the onset of the surge. In the treated ewes, on the other hand, there was an immediate increase in both LH pulse amplitude and the concentration of FSH immediately after the end of bFF treatment at luteolysis, and they remained above control levels for 24 and 16 h respectively. Plasma prolactin levels did not appear to change around the time of luteolysis but showed a marked and significant diurnal rhythm (nadir around noon and peak around midnight) in both groups. The concentrations of prolactin were significantly (P less than 0.001) lower and the preovulatory peak was delayed and reduced in the bFF-treated ewes relative to controls. The onset of oestrus was also significantly (P less than 0.01) delayed by bFF treatment, but the ovulation rates did not differ between the groups. Furthermore, comparisons within or between groups revealed no significant relationships between any of the variables of plasma LH secretion during the follicular phase and the subsequent ovulation rate.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Effect of melatonin on the peripheral concentrations of LH and progesterone after oestrus, and on conception rate in ewes.
It has previously been shown that administration of the indoleamine melatonin to advance the breeding season of ewes is also associated with an increase in ovulation rate and subsequent litter size. Experiment 1 assessed whether, in ewes receiving melatonin to advance the breeding season, the indoleamine acts directly on the corpus luteum to enhance progesterone secretion or indirectly through increased activity of the hypothalamic pulse generator. Six ewes received 3 mg melatonin orally at 15.00 h daily from 22 March onwards, six were induced to ovulate during mid-anoestrus following withdrawal of a progestagen pessary and injection of exogenous gonadotrophin and six acted as naturally ovulating controls. First overt oestrus occurred between 17 May and 8 July in melatonin-treated ewes, between 21 October and 3 January in control ewes and on 8 July in all induced ewes. On days 2 and 10 after the first overt oestrus, melatonin-treated ewes had pulsatile LH activity characteristic of that measured in control ewes ovulating naturally during the breeding season. There was an absence of any pulsatile LH activity in the induced ewes. Progesterone concentrations between days 7 and 12 following oestrus were significantly higher in melatonin-treated than in control and induced ewes, suggesting a luteotrophic role for melatonin. Experiment 2 was carried out to determine whether administration of melatonin commencing after induced ovulation and insemination would alter the endocrine status of the ewe and thereby influence the establishment of pregnancy and embryo survival.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Pulmonary disease at autopsy in patients with the acquired immunodeficiency syndrome.
To characterize the postmortem pulmonary disease and analyze the effectiveness of antemortem diagnosis, we examined the clinical records and autopsy material from 54 patients who died of the acquired immunodeficiency syndrome. At autopsy, all patients had pulmonary disease. One or more specific diagnoses were made in 53, including opportunistic infection, nonopportunistic infection, and Kaposi's sarcoma. Multiple postmortem pulmonary diagnoses were established in 37. Respiratory failure was the most common cause of death. Of the 97 pulmonary disorders discovered at autopsy, only 31 were diagnosed before death. The frequency with which infections were diagnosed during life varied according to the organism, and was significantly higher for Pneumocystis carinii than for cytomegalovirus or bacterial agents. Pulmonary Kaposi's sarcoma was diagnosed in only 7% of patients with autopsy documentation. The yield of diagnostic procedures also varied according to the disease present. Sputum culture was relatively effective in detecting Cryptococcus neoformans and Mycobacterium avium-intracellulare, fiber-optic bronchoscopy was extremely useful for diagnosing P Carinii, and one or more diagnoses were provided in 4 of 7 patients who underwent thoracotomy, but significant disease including cytomegalovirus infection and pulmonary Kaposi's sarcoma was frequently missed. Although the spectrum of lung disease found at autopsy is similar to that observed during life, the frequency of some pathologic processes including cytomegalovirus infection and Kaposi's sarcoma may be underrepresented in antemortem series.
Acquired Immunodeficiency Syndrome↗
Efficacy and complications of transthoracic needle biopsy of lung in patients with Pneumocystis carinii pneumonia and AIDS.
Transthoracic needle biopsy of lung was performed under fluoroscopic guidance in 16 patients with AIDS or suspected AIDS for diagnosing 18 episodes of possible P carinii infection. Diagnostic information was obtained in 15 of 18 cases. P carinii (10) and other infections agents (5) were diagnosed by TNB. The complications were pneumothorax in 44% (17% requiring chest tube drainage) and minor hemoptysis in 11%. Our incidence of pneumothorax following TNB in patients with diseases other than AIDS is 17% with 4.8% requiring chest tube drainage. Although TNB under fluoroscopic guidance is a cost-effective, rapid procedure with a high diagnostic yield, it is frequently complicated by pneumothorax in AIDS patients with diffuse pulmonary disease. This procedure should therefore only be performed in AIDS patients when transbronchial biopsy has failed to provide the diagnosis and prior to considering such patients for open lung biopsy.
Acquired Immunodeficiency Syndrome↗
Differential examination of bronchoalveolar lavage cells in tobacco cigarette and marijuana smokers.
Cells derived from bronchoalveolar lavage (BAL) were obtained from 19 healthy non-smokers (NS) and from 43 healthy smokers of tobacco and/or marijuana. Thirteen subjects smoked tobacco cigarettes only (TS) (mean +/- SE: 17.4 +/- 5.5 pack-years). Thirty subjects smoked marijuana; of these, 14 smoked marijuana only (MS) (149.1 +/- 102.7 joint-years) and 16 smoked marijuana and tobacco (MTS) (43.3 +/- 7.2 joint-years and 18.4 +/- 3.2 pack-years). Cell counts were expressed as total number recovered and as number of cells per milliliter of BAL fluid returned. Cell differentials were performed on Giemsa-stained cytopreps. Total cell number was significantly increased in the MTS, TS, and MS compared with that in the NS (p less than 0.01). Heavy tobacco smoking (greater than 10 pack-years) was associated with higher total cell numbers in BAL than was light tobacco smoking (less than 10 pack-years). The MTS had a higher total BAL cell yield per milliliter than did the TS or the MS (p less than 0.004). Marijuana smoking had a significant effect on cell yield independent of the presence or absence of concomitant tobacco smoking (p less than 0.05). Macrophages were the predominant cells in the BAL of TS, MS, and MTS, as well as in the BAL of NS (greater than or equal to 90%). The number of neutrophils (as total recovered or per milliliter of BAL fluid) was significantly higher in the BAL fluid of all MTS and TS than in that of NS (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Cytomegalovirus pneumonitis in patients with AIDS. Findings in an autopsy series.
Cytomegalovirus (CMV) pneumonitis is a common complication of AIDS. With the development of potentially effective drug therapy, the indications for treatment and best means of diagnosis have become issues of practical importance. We reviewed the clinical records and autopsy material from 54 patients dying with AIDS, 39 (72 percent) of whom had CMV infection documented postmortem by culture and the presence of inclusion bodies. Of the patients with CMV infection, disseminated disease was documented in 23 (59 percent) and pneumonitis in 31 (80 percent). Although the majority of patients with CMV pneumonitis had additional forms of pulmonary pathology, CMV was the only causative agent identified in two patients with severe pulmonary disease. Since CMV can cause severe lung damage and disseminated infection in patients with AIDS, specific treatment may be beneficial. Improved diagnostic technology is needed in this area.
Acquired Immunodeficiency Syndrome↗
Induction of ovulation during anoestrus in two breeds of sheep with multiple injections of LH alone or in combination with FSH.
The gonadotrophic requirements for the induction of ovulation and formation of a viable corpus luteum in two breeds of seasonally anoestrous sheep of differing fecundity was investigated. Welsh Mountain (n = 20) and Damline ewes (n = 19) were given LH or FSH either alone or in combination. Luteinizing hormone was injected i.v. at an increasing frequency for 72 h (one injection every 3 h for 24 h, one every 2 h for 24 h, and one every hour for 24 h) and FSH was injected in an identical manner for the first 36 h of treatment. Exogenous LH alone and in combination with FSH induced a preovulatory LH surge in all 19 ewes and ovulation in 18 out of 19 ewes of both breeds. However exogenous FSH alone was ineffective. The incidence of normal corpus luteum function in ewes induced to ovulate was low and not related to treatment, timing or magnitude of the LH/FSH surge. It is concluded that in both breeds studied it is the infrequency of LH pulses which limits the development of preovulatory follicles during seasonal anoestrus, that the requirement for FSH remains unknown, and that the induction of inadequate corpora lutea during seasonal anoestrus reflects either defects in hormonal priming of the preovulatory follicle and/or inappropriate luteotrophic support after ovulation.
Anestrus↗
The roles of inhibin and gonadotrophin-releasing hormone in the control of gonadotrophin secretion in the ewe.
The respective roles and relative importance of ovarian inhibition and hypothalamic stimulation in the differential control of the secretion of FSH and LH were studied in the ewe. In the first experiment two groups of ten intact ewes were injected i.v. twice daily with 9 ml charcoal-extracted bovine follicular fluid (bFF), a preparation rich in inhibin (3.65 ku./ml), throughout the luteal phase of the oestrous cycle. Compared with the control ewes, this treatment significantly reduced pituitary and plasma FSH concentrations and increased the frequency and amplitude of the LH pulses, but did not affect pituitary LH concentrations. In a second experiment, five control and five bFF-treated ewes from experiment 1 were ovariectomized and the injection regime was altered to 2.5 ml s.c. every 8 h. This treatment was maintained for 21 days. In control ewes, plasma FSH concentrations rose significantly within 12 h and continued to rise for 3-4 days. Treatment with bFF abolished this increase and maintained plasma FSH concentrations below those observed in intact ewes. The rise in mean plasma LH concentrations evoked by ovariectomy was also partially inhibited in the bFF-treated ewes. The response to the gonadotrophin-releasing hormone (GnRH) agonist buserelin (5 micrograms i.v.) was measured 6, 12 and 18 days after ovariectomy. In control ewes the agonist consistently evoked large surges of both hormones but in bFF-treated ewes the FSH response was completely blocked and the initial phase of the LH response (the first 'pool') was greatly reduced. In experiment 3, six ewes were ovariectomized and passively immunized against GnRH 3 days after oestrus. The increase in plasma LH which normally follows ovariectomy was completely abolished and mean concentrations remained very low and did not change over the following 14 days. In contrast, mean FSH concentrations rose significantly within 12 h of ovariectomy and continued to rise until the third day, after which they fell gradually. Treating three of the ewes with bFF (2.5 ml s.c. every 8 h) 8 days after ovariectomy and immunization further reduced the FSH concentrations. When the ewes were injected repeatedly (200 ng i.v., hourly for 5 h) with [D-penicillamine-(But)6]-GnRH(1-9)nonapeptide-ethylamide, a synthetic GnRH analogue which does not bind to the antiserum, there was a rapid rise in the secretion of LH in both control and bFF-treated animals but, as with the responses to buserelin, the initial response was significantly lower in bFF-treated than in control ewes.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Changes in FSH and the pulsatile secretion of LH during treatment of ewes with bovine follicular fluid throughout the luteal phase of the oestrous cycle.
Treatment of Damline ewes with twice-daily i.v. injections of bovine follicular fluid during the luteal phase for 10 or 2 days before prostaglandin-induced luteolysis resulted in a delay in the onset of oestrous behaviour and a marginal increase in ovulation rate. During the treatment cycle, blood samples were withdrawn at 15-min intervals for 25 h from 08.00 h on days 1, 6 and 10 (day 0 = oestrus). At all three stages of the luteal phase, plasma FSH concentrations were suppressed relative to controls 3 h after the 09.00 h injection of follicular fluid and remained low until 06.00 h on the following day. In the 10-day treatment group LH pulse amplitude was significantly greater than that of controls on days 6 and 10. Pulse frequency remained high throughout treatment and was significantly higher relative to controls on day 10 despite normal progesterone levels. The results suggest that the higher pulsatile LH secretion during the luteal phase is due to reduced negative feedback effects of oestradiol occurring as a result of the follicular fluid-induced reduction in FSH.
Animals↗
Influenza B virus model of Reye's syndrome in mice: the effect of aspirin.
Aspirin is a possible cofactor with influenza B virus in Reye's syndrome. In an attempt to determine whether single or multiple doses of acetylsalicylic acid (ASA) alter mortality in an influenza B virus mouse model of Reye's syndrome, either ASA (300 to 667 mg/kg) or saline was given intraperitoneally to 3-week-old Balb/c mice. Two hours later, one median lethal dose (LD50) of influenza B/Lee virus was given intravenously. Mortality was not significantly increased by the single ASA dose. Blood ASA levels rose as high as 68 mg/dl. The average ASA blood levels in mice 12 hours after receiving the virus plus 667 mg/kg ASA was 22.6 mg/dl, which was significantly higher than the 3.4 mg/dl for mice who received saline plus ASA. No significant increase in mortality occurred in mice given 67 mg/kg ASA twice daily for 7 days and one LD50 dose of virus on day 4. We conclude that a single dose of ASA at up to half the median lethal dose or multiple doses of ASA do not significantly increase mortality in this influenza virus model of Reye's syndrome. However, influenza B virus infection appears to interfere with ASA metabolism.
Animals↗
Enhanced proliferation of WI38 cells in the presence of glucocorticoid-conditioned medium.
The addition of hydrocortisone (HC) or dexamethasone (DEX) to WI38 cells at subcultivation is known to result in increased saturation densities (20-40%). We report that maximal increases in saturation density are, however, only observed if HC is added to the culture shortly after subcultivation. We have found that the proliferative response of WI38 cells to glucocorticoids is mediated by a secondary stimulatory factor(s) present in medium-conditioned by cells in the presence of the hormone. Control cultures refed with medium conditioned in the presence of HC for the first 24 h after seeding (24 h HC-CM) achieve saturation densities 20-40% higher than cultures refed with either medium conditioned in the absence of the hormone (24 h CM) or 24 h CM supplemented with fresh HC. Furthermore, WI38 cultures remain responsive to the stimulatory activity present in 24 h HC-CM throughout the growth cycle. The stimulatory effects of 24 h HC-CM are enhanced by repeatedly refeeding cultures; WI38 cells refed every 2 days with 24 h HC-CM demonstrate an extended period of logarithmic growth and achieve densities 2-3 times higher than controls. A preliminary characterization of this activity shows it to be of low molecular weight (MW) (dialyzable using 12 000 MW cut-off tubing) and heat-stable (75 degrees C).
Cell Division↗