Alveolar metabolism of natural vs. synthetic surfactants in preterm newborn rabbits

We compared the recoveries of four surfactant preparations: two natural [term fetal rabbit surfactant (FRS) and adult rabbit surfactant (ARS)] and two commercially available preparations [apoprotein-based Survanta (S) and synthetic Exosurf (E)] from 27-day gestation rabbit pups treated at birth and ventilated up to 120 min. At 5, 60, and 120 min, we measured the recovery of the heavy-aggregate, metabolically active form (H) and the light-aggregate, nonsurface active metabolic breakdown form (L) of alveolar surfactant and determined the phospholipid content and composition of the intracellularly stored lamellar body (LB) pool. Pups treated with FRS had <15% loss of H by 2 h. ARS-treated pups had a >50% loss of H by 1 h, and E- and S-treated pups had approximately 50% loss by 5 min, with a slower rate of continuing loss of up to 80% by 2 h. The major losses of H phospholipid were not explained by the L-form recovery. LB phospholipid significantly increased only in the E-treated pups and only at 2 h. FRS provides a biologically active form (H) of surfactant that appeared to remain in the airway for a significantly longer time than the other surfactant preparations. The unique properties of FRS merit further study.

Generation of female genital tract antibody responses by local or central (common) mucosal immunization

Genital antibody responses were compared in female mice immunized intravaginally (i.vag.) or intranasally (i.n.) with a bacterial protein antigen (AgI/II of Streptococcus mutans) coupled to the B subunit of cholera toxin. Serum and salivary antibodies were also evaluated as measures of disseminated mucosal and systemic responses. Although i.vag. immunization induced local vaginal immunoglobulin A (IgA) and IgG antibody responses, these were not disseminated to a remote secretion, the saliva, and only modest levels of serum antibodies were generated. In contrast, i.n. immunization was substantially more effective at inducing IgA and IgG antibody responses in the genital tract and in the circulation, as well as at inducing IgA antibodies in the saliva. Moreover, mucosal and systemic antibodies induced by i.n. immunization persisted for at least 12 months. Analysis of the molecular form of genital IgA indicated that the majority of both total IgA and specific IgA antibody was polymeric, and likely derived from the common mucosal immune system.

Comparison of a live attenuated and an inactivated varicella vaccine to boost the varicella-specific immune response in seropositive people 55 years of age and older

Healthy, varicella-zoster virus (VZV)-seropositive subjects, aged 55-89 years (mean age 66 years), received either 4000 PFU of live, attenuated VZV vaccine (n=85) or an equal volume of this vaccine that was heat-inactivated (n=82). Both vaccines significantly boosted VZV antibody (enzyme immunoassay) and gamma-interferon production by peripheral blood mononuclear cells stimulated by VZV antigen. These responses returned to baseline by 12 months. Circulating mononuclear cells that proliferated in response to VZV antigen were significantly more numerous (responder cell frequency assay) after either vaccine, and persisted with a half-life of 17. 5-21.3 months. There were no differences in immune response to either vaccine in this older age cohort.

Lipid-laden macrophages in the tracheal aspirate of ventilated neonates receiving Intralipid: A pilot study

Lipid-laden macrophages (LLM) in tracheal aspirates are reported to be pathognomonic findings in exo- and endogenous lipoid pneumonia in adults. A pilot study was carried out to evaluate the effect of lipid infusion on the LLM index of the tracheal aspirates from ventilated neonates. All intubated infants were eligible for the study. Infants receiving parenteral nutrition had intravenous (IV) lipid introduced by 4-7 days of age; most samples after 7 days were from infants receiving IV lipid. Four infants received minimal gastric feeding; none had evidence of aspiration pneumonia. Tracheal aspirates from 28 infants were analyzed for the LLM index. Alveolar macrophages were graded 0-4 in direct relation to the amount of lipid per cell. One hundred macrophages were graded; the maximum possible LLM index was 400. Two hundred forty-five of 387 tracheal aspirate samples were acceptable for analysis. LLM indices increased during the first week after birth; the mean LLM index then continued in the same range, but with a wide distribution of individual values. The mean LLM index from infants receiving an IV lipid infusion during days 4-7 was 87.9 (SD = 44.8), and was significantly higher compared to 58.7 (SD = 40.8) in infants receiving no IV lipid (P < 0. 003). Tracheal aspirates from infants with and without IV lipid infusion yielded many LLM index values >100. These observations invalidate the use of the LLM index >100 as proof of aspiration pneumonia in this group of infants.

Supply and demand for radiation therapists: a United States perspective for 1997-2002

The purpose of this paper is to review the current and future employment plans of radiation therapists and administrators that employ them so that the supply and demand for these individuals is quantified. The survey was funded by the American Society of Radiologic Technologists and implemented by the Task Force on Human Resources. In April 1997 a questionnaire was mailed to a sample of radiation therapy administrators identified by the mailing list of the Society of Radiation Oncology Administrators (SROA). Another questionnaire was mailed to a sample of radiation therapists holding active certificates with the American Registry of Radiologic Technologists. Results of the survey indicated an increased demand for radiation therapists based on plans for facility expansion. Individuals anticipating retirement in the next five years ranged from 7% of the radiation therapists and 12% of the administrators surveyed. A model was developed which projected a shortfall of therapists ranging from 0% (-13 positions) in 1998 to 3% (-403 positions) projected for 2002. The paper concludes that the supply of radiation therapists did not meet the demand in the time period measured; 1998-2002. An increase in newly educated radiation therapists is needed to fill the openings created by those leaving the field. The survey should be repeated at successive intervals to accurately track and project both the supply of and the demand for radiation therapists.

Use of a live attenuated varicella vaccine to boost varicella-specific immune responses in seropositive people 55 years of age and older: duration of booster effect

Varicella-zoster virus (VZV)-specific T cell immunity was measured in 130 persons > or = 55 years of age 6 years after they received a live attenuated VZV vaccine. Circulating T cells, which proliferated in vitro in response to VZV antigen, were enumerated (VZV responder cell frequency assay). Six years after the booster vaccination, the VZV-responding cell frequency (1/61,000 circulating cells) was still significantly (P < .05) improved over the baseline measurements (1/70,000) and appears to have diminished the expected decline in frequency as these vaccinees aged (to 1/86,000). Ten herpes-zoster--like clinical events were recorded. Although the frequency of these events, approximately 1/100 patient-years, is within the expected range of such events for this age cohort, the number of lesions was small, there was very little pain, and there was no postherpetic neuralgia. These results support the development of a vaccine to prevent or attenuate herpes zoster.

Measles, mumps, rubella, and varicella combination vaccine: safety and immunogenicity alone and in combination with other vaccines given to children. Measles, Mumps, Rubella, Varicella Vaccine Study Group

Eight hundred and twelve children, 12 months to 3.5 years of age, were enrolled in two clinical studies to evaluate the safety and immunogenicity of a live, attenuated combination vaccine for measles, mumps, rubella, and varicella (MMRV). Children were enrolled in one of two randomized, multicenter studies, involving administration of (1) MMRV and placebo vs. measles, mumps, and rubella vaccine (M-M-R(II)) and varicella-zoster virus vaccine (VARIVAX), given at separate anatomic sites at the same office visit; or (2) MMRV, DTaP (diphtheria, tetanus, and acellular pertussis vaccine) and OPV (oral polio vaccine) vs. M-M-R(II), DTaP, and OPV, with VARIVAX given 6 weeks later. All vaccine regimens were generally well tolerated. More than 95% of vaccinees seroconverted for measles, mumps, rubella, and varicella, regardless of the vaccine or regimen used. In each study, the level of antibody titer to varicella virus was significantly lower in vaccinees receiving MMRV than in those who received VARIVAX in a separate syringe.

Necrotizing funisitis associated with Actinomyces meyeri infection: a case report

Necrotizing funisitis is associated with an increased rate of stillbirth, perinatal infection, and preterm delivery. No one organism has been associated with necrotizing funisitis, although this condition has been linked with congenital syphilis in some studies. We report a case of necrotizing funisitis in a 24-year-old G2P0A2 woman who experienced preterm labor at 31 weeks of gestation. Examination of the placenta revealed severe chorioamnionitis and necrotizing funisitis; large numbers of gram-positive filamentous branching organisms could be seen on the surface of the cord and within Wharton jelly. Initial cultures of the placenta, which had not been maintained under anaerobic conditions after delivery, were negative. A fragment of the cord was then homogenized; anaerobic culture on brain-heart infusion agar yielded Actinomyces meyeri. This organism usually resides in the periodontal sulcus and has not been previously reported in the female genital tract. The mother gave a history of a dental abscess that flared up and drained with each of her three pregnancies; the pain was particularly severe during the last 2 months of this pregnancy, so she had the tooth removed after delivery. The infant was treated for prematurity and presumed sepsis and did well.

Autoradiographic localization and effects of exogenous radioactively labelled surfactant in the lung of the prematurely delivered fetal rabbit

Adult rabbit lung surfactant was radioactively labelled with [3H]palmitate and isolated by centrifugation. This material was instilled into the trachea of fetal rabbits prematurely delivered on the 27th gestational day. A similar preparation of unlabelled surfactant was used to measure the effects on pressure-volume characteristics in lungs of 27th day fetuses. Tissue sections were prepared from the lungs of all animals and morphometric and autoradiographic determinations made. Surfactant instillation improved pressure-volume relationships in fetal rabbit lungs. Histologically, although only the middle right lobe seemed to show significant qualitative improvement in expansion after surfactant treatment, quantitative assessment indicated that the surfactant preparation had significantly increased the mean alveolar cross-sectional areas in all three lobes of right lungs. In addition, distribution of autoradiographic grains indicated that 8-25% were located over the alveolar spaces while approximately half this percentage was present over tissue at the level of the alveolus. These results indicate that intratracheal instillation of surfactant supplements the endogenous surfactant at the level of the alveolus.

Seasonal affective disorder and season-dependent abnormalities of melatonin suppression by light

Twelve patients with seasonal affective disorder (SAD) and eleven normal controls were exposed to 2000 lux and 300 lux of artificial full-spectrum light on consecutive nights during the winter. Suppression of melatonin secretion under the two light intensities was measured and the difference between their effects was taken as a measure of light sensitivity. The test was repeated in summer in both groups, when the SAD subjects were well. The SAD but not the normal group showed a significant seasonal variation in sensitivity to light. There was evidence of supersensitivity in the winter but also of subsensitivity to light in the summer.

Clinical experience with phototherapy

Thirty subjects with seasonal affective disorder (SAD) and three subjects with a non-seasonal depression had a trial of phototherapy in an open assessment of the feasibility of phototherapy in clinical practice. 43% of the SAD subjects met the criteria for 'successful treatment', but none of the subjects with non-seasonal depression showed any response. Due to personal constraints, not all were able to receive light exposure up to the amount recommended. Results indicated that the more severe the atypical symptoms of depression the more likely they were to respond to phototherapy, while greater severity of 'endogenous' symptoms predicted a poor response. Several subjects used the trial to decide whether to purchase equipment to continue treatment. Follow-up information on these subjects is presented.

A comparison of normal, bipolar and seasonal affective disorder subjects using the Seasonal Pattern Assessment Questionnaire

The Seasonal Pattern Assessment Questionnaire is an instrument for retrospective self-rating of change in mood and vegetative functions with the seasons. It has been used in studies to identify and characterise patients with Seasonal Affective Disorder (SAD) in three countries. In this paper, the test-retest reliability of all items and the sensitivity to differences between groups have been investigated. Clear differences were found between the SAD group and a normal group. A group of bipolar affective disorder patients had intermediate scores on reported seasonal changes between the normal and SAD groups. All groups reported significant changes in mood and vegetative functions during the winter in the direction symptomatic for SAD suggesting that SAD patients may suffer an exaggerated form of a normal seasonal variation.

Early intravenous indomethacin prolongs respiratory support in very low birth weight infants

Infants weighing 1500 g at birth requiring either intermittent positive pressure ventilation or continuous positive airway pressure by 12 hours of age were entered in a randomized double blind controlled trial to test the efficacy of early intravenous indomethacin therapy in preventing chronic pulmonary disease of prematurity. Of the 30 newborns enrolled, 15 were treated with indomethacin and 15 were treated with placebo at 12, 24 and 36 hours of age. The groups were similar for birth weight, gestational age, sex, hyaline membrane disease and intracranial hemorrhage. Infants in the placebo group were successfully weaned from intermittent positive pressure ventilation at an earlier age than infants in the indomethacin group (p less than 0.05). Furthermore, chronic pulmonary disease of prematurity was similar in the two groups despite a reduction in the incidence of patent ductus arteriosus in the indomethacin group.

Characteristics of glucose-stimulated breathing movements in human fetuses with intrauterine growth retardation

The characteristics of fetal breathing movements were analyzed in 13 fetuses who were intrauterine growth retarded and in a comparison group of 13 well-grown fetuses. The numbers of minutes of breathing activity per hour were similar for the two groups; the increase (p less than 0.05) after maternally administered glucose was due to longer (p less than 0.05) and more frequent (p less than 0.05) breathing episodes, and was mainly deep breathing. The deep breathing rate increased significantly (p less than 0.05) after glucose. The two groups exhibited similar low occurrences of shallow breathing (less than 5 minutes per hour) throughout the experiments. No significant differences could be demonstrated between intrauterine growth-retarded and well-grown fetuses with respect to the amount, rate, and pattern of breathing activity during fasting or after oral administration of glucose to the mother.

The effect of maternal glucose infusion on breathing movements in human fetuses with intrauterine growth retardation

forty-nine patients with suspected intrauterine growth retardation (IUGR) were studied under rigid experimental conditions to determine baseline fetal breathing movement (FBM) activity and the response to 90-minute maternal glucose infusion, as compared to that of normal control subjects. Patients with IUGR showed a normal amount of FBMs during maternal fasting. All groups exhibited a significant increase in FBMs after glucose was administered. During the final 60 minutes of the glucose infusion, the severe IUGR group (weight for gestational age less than the third percentile) showed less FBM activity (p less than 0.01) than the other study and control groups.

Measurement of Tensile Strength of Natural Rubber Vulcanizates at Elevated Temperature

The tensile strength of test pieces made from natural rubber vulcanizates drops abruptly at a critical temperature which can vary from 40 to 130°C. This variation in critical temperature is shown here to be a result of the variation in critical cut length with temperature. When the naturally occurring flaws in the test piece are smaller than the critical cut length, high tensile strength values occur, but when the flaws are longer than the critical cut length, low tensile strength values occur. The critical cut length decreases as the temperature increases, and the abrupt drop in tensile strength occurs as the critical cut length reaches the natural flaw size in the test piece. The natural flaw size in tensile test pieces depends on the sharpness of the cutter, and for tensile strength measurements at elevated temperature, it is shown that even a slightly blunt cutter may give markedly different results from a sharp one.

Developmental study of a lamellar body fraction isolated from human amniotic fluid

Several properties of a pellet fraction obtained on centrifuging amniotic fluid at 10,000 X g for 20 min were investigated. From these analyses, we defined a developmental profile which appears to describe the maturational process of the fetal lung surfactant system. At 14 to 18 wk gestation, the pellet fraction consisted of membrane-bound vesicles without internal lamellae. The phospholipid composition did not resemble that of surfactant, the major phospholipid being sphingomyelin. This stage, designated as presurfactant, persisted until 30 to 32 wk gestation. After this time, the phospholipid concentration of the pellet fraction increased continuously throughout development, and gradual but continuous changes in phospholipid composition were observed. Lecithin and phosphatidylinositol increased between 30 and 35 wk gestation. Interruption of pregnancies at this stage, termed onset of surfactant synthesis, resulted in 100% incidence of respiratory distress syndrome. From 36 wk gestation to postterm, the pellet fraction contained structures with the characteristic morphology of the lamellar inclusion bodies. The presence of single membrane components in these preparations did not contribute to the phospholipid composition. Early formed lamellar bodies lacked phosphatidylglycerol and had a high content of phosphatidylinositol. Once phosphatidylglycerol appeared in the lamellar body fraction, it continued to increase, accompanied by a decrease in phosphatidylinositol with little change in lecithin. A phosphatidylglycerol value of greater than 1% of the total phospholipids appeared to represent the stage of maturity at which there was no risk of respiratory distress syndrome.

Overt diabetes in pregnancy

Of 45 diabetic pregnancies, 80% were Class C, D, or R. The perinatal mortality rate was 4.4% (corrected 2.2%); however, neonatal morbidity was high. Of the infants, 28% developed respiratory distress syndrome (RDS); 18%, asphyxia; and 42%, hypoglycemia. Thus, the woman with overt diabetes needs delivery in an institution where neonatal expertise and modern neonatal facilities exist. Of the mother 28% had a family history that was negative for diabetes mellitus. Four neonates developed RDS despite mature lecithin/sphingomyelin ratios.