Evidence for positive long- and short-term effects of vaccinations against COVID-19 in wearable sensor metrics

Vaccines are among the most powerful tools to combat the COVID-19 pandemic. They are highly effective against infection and substantially reduce the risk of severe disease, hospitalization, ICU admission, and death. However, their potential for attenuating long-term changes in personal health and health-related wellbeing after a SARS-CoV-2 infection remains a subject of debate. Such effects can be effectively monitored at the individual level by analyzing physiological data collected by consumer-grade wearable sensors. Here, we investigate changes in resting heart rate, daily physical activity, and sleep duration around a SARS-CoV-2 infection stratified by vaccination status. Data were collected over a period of 2 years in the context of the German Corona Data Donation Project with around 190,000 monthly active participants. Compared to their unvaccinated counterparts, we find that vaccinated individuals, on average, experience smaller changes in their vital data that also return to normal levels more quickly. Likewise, extreme changes in vitals during the acute phase of the disease occur less frequently in vaccinated individuals. Our results solidify evidence that vaccines can mitigate long-term detrimental effects of SARS-CoV-2 infections both in terms of duration and magnitude. Furthermore, they demonstrate the value of large-scale, high-resolution wearable sensor data in public health research.

Estimating the share of SARS-CoV-2-immunologically naïve individuals in Germany up to June 2022

After the winter of 2021/2022, the coronavirus disease 2019 (COVID-19) pandemic had reached a phase where a considerable number of people in Germany have been either infected with a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, vaccinated or both, the full extent of which was difficult to estimate, however, because infection counts suffer from under-reporting, and the overlap between the vaccinated and recovered subpopulations is unknown. Yet, reliable estimates regarding population-wide susceptibility were of considerable interest: Since both previous infection and vaccination reduce the risk of severe disease, a low share of immunologically naïve individuals lowers the probability of further severe outbreaks, given that emerging variants do not escape the acquired susceptibility reduction. Here, we estimate the share of immunologically naïve individuals by age group for each of the sixteen German federal states by integrating an infectious-disease model based on weekly incidences of SARS-CoV-2 infections in the national surveillance system and vaccine uptake, as well as assumptions regarding under-ascertainment. We estimate a median share of 5.6% of individuals in the German population have neither been in contact with vaccine nor any variant up to 31 May 2022 (quartile range [2.5%-8.5%]). For the adult population at higher risk of severe disease, this figure is reduced to 3.8% [1.6%-5.9%] for ages 18-59 and 2.1% [1.0%-3.4%] for ages 60 and above. However, estimates vary between German states mostly due to heterogeneous vaccine uptake. Excluding Omicron infections from the analysis, 16.3% [14.1%-17.9%] of the population in Germany, across all ages, are estimated to be immunologically naïve, highlighting the large impact the first two Omicron waves had until the beginning of summer in 2022. The method developed here might be useful for similar estimations in other countries or future outbreaks of other infectious diseases.

Prevalence of Positive COVID-19 Test Results Collected by Digital Self-report in the US and Germany

This cohort study examines traditional surveillance and self-reported COVID-19 test result data collected from independent smartphone app–based studies in the US and Germany.

Modeling the impact of the Omicron infection wave in Germany

In November 2021, the first infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant of concern (VOC) B.1.1.529 ('Omicron') was reported in Germany, alongside global reports of reduced vaccine efficacy (VE) against infections with this variant. The potential threat posed by its rapid spread in Germany was, at the time, difficult to predict. We developed a variant-dependent population-averaged susceptible-exposed-infected-recovered infectious-disease model that included information about variant-specific and waning VEs based on empirical data available at the time. Compared to other approaches, our method aimed for minimal structural and computational complexity and therefore enabled us to respond to changes in the situation in a more agile manner while still being able to analyze the potential influence of (non-)pharmaceutical interventions (NPIs) on the emerging crisis. Thus, the model allowed us to estimate potential courses of upcoming infection waves in Germany, focusing on the corresponding burden on intensive care units (ICUs), the efficacy of contact reduction strategies, and the success of the booster vaccine rollout campaign. We expected a large cumulative number of infections with the VOC Omicron in Germany with ICU occupancy likely remaining below capacity, nevertheless, even without additional NPIs. The projected figures were in line with the actual Omicron waves that were subsequently observed in Germany with respective peaks occurring in mid-February and mid-March. Most surprisingly, our model showed that early, strict, and short contact reductions could have led to a strong 'rebound' effect with high incidences after the end of the respective NPIs, despite a potentially successful booster campaign. The results presented here informed legislation in Germany. The methodology developed in this study might be used to estimate the impact of future waves of COVID-19 or other infectious diseases.

Hot electron plasmon-protected solar cell

A solar cell based on a hot electron plasmon protection effect is proposed and made plausible by simulations, non-local modeling of the response, and quantum mechanical calculations. In this cell, a thin-film, plasmonic metamaterial structure acts as both an efficient photon absorber in the visible frequency range and a plasmonic resonator in the IR range, the latter of which absorbs and protects against phonon emission the free energy of the hot electrons in an adjacent semiconductor junction. We show that in this structure, electron-plasmon scattering is much more efficient than electron-phonon scattering in cooling-off hot electrons, and the plasmon-stored energy is recoverable as an additional cell voltage. The proposed structure could become a prototype of a new generation of high efficiency solar cells.

Nanoscope based on nanowaveguides

The far field spatial resolution of conventional optical lenses is of the order of the wavelength of light, due to loss in the far field of evanescent, near electromagnetic field components. We show that subwavelength details can be restored in the far field with an array of divergent nanowaveguides, which map the discretized, subwavelength image of an object into a magnified image observable with a conventional optical microscope. We demonstrate in simulations that metallic nanowires, nanocoaxes, and nanogrooves can be used as such nanowaveguides. Thus, an optical microscope capable of subwavelength resolution - a nanoscope - can be produced, with possible applications in a variety of fields where nanoscale optical imaging is of value.

Massive transfusion--evaluation of current clinical practice and outcome in two large teaching hospital trusts in Northern England

BACKGROUND AND OBJECTIVES

Although numerous guidelines exist for the management of massive blood loss, there have been few data confirming whether these guidelines are observed in practice or whether compliance results in improved outcome. We have performed a retrospective audit of cases of massive transfusion in two major teaching hospital trusts in Northern England to investigate the use of blood components and patient outcome.

MATERIALS AND METHODS

The massive transfusion population was electronically derived from a list of all blood component transfusions in 2006. Data from the intensive care and patient administration databases established hospital outcome. Factors independently predictive of survival were identified by logistic regression. Data are presented as medians and interquartile ranges. Odds ratios (OR) are given with 95% confidence intervals.

RESULTS

Two hundred and four patients had a massive transfusion. Although only 1.3% of all transfused patients, the massive transfusion group used 10% of the total blood products. Their mortality rate was 34%. Factors independently predictive of survival were: a ratio of fresh frozen plasma: red blood cells > 1.1, OR 7.22 (1.95-26.68), and elective surgery, OR 4.56 (1.88-11.05). Factors independently predictive of death were: age (per year), OR 0.97 (0.95-0.99), liver disease, OR 0.25 (0.09-0.70), male gender, OR 0.41 (0.19-0.89), vascular surgery, OR 0.34 (0.12-0.96) and number of adult packs of platelets transfused, OR 0.69 (0.57-0.83).

CONCLUSION

Massive transfusion occurs rarely but has a high mortality and requires a disproportionate amount of blood products. An increased ratio of fresh frozen plasma to red blood cells was associated with improved outcome.

Cyclosporin immunosuppression of sheep: pharmacokinetics and allograft survival

A chronically immunosuppressed sheep model was established using a regimen of cyclosporin A (CsA; 2-3mg/kg twice daily) and ketoconazole (10mg/kg twice daily). Blood CsA concentrations reached a steady-state after 17 days of treatment. The clearance of CsA decreased from a mean (95% CI) of 9.47 (6.2-12.7)ml/min/kg after a single (first) dose (3mg/kg i.v.) to 1.62 (1.38-1.86)ml/min/kg after 18 days of CsA (3mg/kg i.v. twice daily) co-administration with ketoconazole. These data indicated that the combination of CsA and ketoconazole could be used to give stable high concentrations of CsA in the sheep. Using this regimen in the sheep, the long-term survival of skin allografts was monitored as an indicator of effective immunosuppression. CsA in blood was measured daily and CsA dose adjusted to various target concentration ranges. Provided that the trough concentration of blood CsA was maintained between 1500-2500 mg/l, long-term healthy skin allografts were maintained on the sheep without significant adverse effects on haematological or biochemical parameters.

Dispersion of the temperature dependence of the retardance in SiO(2) and MgF(2)

We have directly measured the retardance versus temperature for single-crystal quartz (SiO(2)) and magnesium fluoride (MgF(2)) at wavelengths of 633, 788, 1318, and 1539 nm and over a temperature range of 24-80 degrees C. To our knowledge, the temperature dependence of retardance for these two materials has not been directly measured. We compared our direct measurements of the normalized temperature derivative of the retardance gamma with derived values from previously reported indirect measurements and found our results to be in agreement and our measurement uncertainties to be typically a factor of 4 smaller. Our overall mean value for gamma(SiO(2)) is -1.23 x 10(-4) with a combined standard uncertainty of 0.02 x 10(-4) and little wavelength dependence over the 633-1539-nm range. Our overall mean value for gamma(MgF(2)) is -5.37 x 10(-5) with a combined standard uncertainty of 0.17 x 10(-5) and with a small wavelength dependence over the 633-1539-nm range.

Validation of a new scoring system for the assessment of clinical trial research of oral mucositis induced by radiation or chemotherapy. Mucositis Study Group

BACKGROUND

An impediment to mucositis research has been the lack of an accepted, validated scoring system. The objective of this study was to design, test, and validate a new scoring system for mucositis that can be used easily, is reproducible, and provides an accurate system for research applications.

METHODS

A panel of experts, convened to design an objective, simple, and reproducible assessment tool to evaluate mucositis with specific application to multicenter clinical trials, developed a scale that measured objective and subjective indicators of mucositis. Nine centers participated in the study's validation. Paired investigators at each center evaluated patients receiving chemotherapy or head and neck radiation. Objective measures of mucositis evaluated ulceration/pseudomembrane formation and erythema. Subjective outcomes of mouth pain, ability to swallow, and function were measured. Analgesia use for mouth sensitivity was recorded.

RESULTS

One hundred eight chemotherapy and 56 radiation therapy patients were evaluated. Seventy-eight percent of chemotherapy patients and 64% of radiation therapy patients had clinically significant mucositis. Cumulative daily mucositis scores demonstrated a high correlation among observers. Using area under the curve analysis, it was found that for chemotherapy patients, the highest correlations (correlation coefficient > 0.92) occurred for the scores that selected the three highest daily values over the course of mucositis assessment. High interobserver correlations were noted for patients receiving radiation therapy. Objective mucositis scores demonstrated strong correlation with symptoms.

CONCLUSIONS

The scoring system evaluated was easily used, showed high interobserver reproducibility, was responsive over time, and measured those elements deemed to be associated with mucositis. The use of concomitant symptomatic measurements appeared to be unnecessary.

Validation of a new scoring system for the assessment of clinical trial research of oral mucositis induced by radiation or chemotherapy. Mucositis Study Group

BACKGROUND

An impediment to mucositis research has been the lack of an accepted, validated scoring system. The objective of this study was to design, test, and validate a new scoring system for mucositis that can be used easily, is reproducible, and provides an accurate system for research applications.

METHODS

A panel of experts, convened to design an objective, simple, and reproducible assessment tool to evaluate mucositis with specific application to multicenter clinical trials, developed a scale that measured objective and subjective indicators of mucositis. Nine centers participated in the study's validation. Paired investigators at each center evaluated patients receiving chemotherapy or head and neck radiation. Objective measures of mucositis evaluated ulceration/pseudomembrane formation and erythema. Subjective outcomes of mouth pain, ability to swallow, and function were measured. Analgesia use for mouth sensitivity was recorded.

RESULTS

One hundred eight chemotherapy and 56 radiation therapy patients were evaluated. Seventy-eight percent of chemotherapy patients and 64% of radiation therapy patients had clinically significant mucositis. Cumulative daily mucositis scores demonstrated a high correlation among observers. Using area under the curve analysis, it was found that for chemotherapy patients, the highest correlations (correlation coefficient > 0.92) occurred for the scores that selected the three highest daily values over the course of mucositis assessment. High interobserver correlations were noted for patients receiving radiation therapy. Objective mucositis scores demonstrated strong correlation with symptoms.

CONCLUSIONS

The scoring system evaluated was easily used, showed high interobserver reproducibility, was responsive over time, and measured those elements deemed to be associated with mucositis. The use of concomitant symptomatic measurements appeared to be unnecessary.

Orthotopic xenografts of human melanoma and colonic and ovarian carcinoma in sheep to evaluate radioimmunotherapy

Extrapolation to humans from experimental radioimmunotherapy in nude mouse xenograft models is confounded by large relative tumour size and small volume of distribution in mice allowing tumour uptake of radiolabelled antibodies unattainable in patients. Our large animal model of human tumours in cyclosporin-immunosuppressed sheep demonstrated tumour uptake of targeted radiolabelled monoclonal antibodies comparable with uptakes reported in clinical trials. Sheep immunosuppression with daily intravenous cyclosporin augmented by oral ketoconazole maintained trough blood levels of cyclosporin within the range 1000-1500 ng ml(-1). Human tumour cells were transplanted orthotopically by inoculation of 10(7) cells: SKMEL melanoma subcutaneously; LS174T and HT29 colon carcinoma into bowel, peritoneum and liver; and JAM ovarian carcinoma into ovary and peritoneum. Tumour xenografts grew at all sites within 3 weeks of inoculation, preserving characteristic morphology without evidence of necrosis or host rejection. Lymphatic metastasis was demonstrated in regional nodes draining xenografts of melanoma and ovarian carcinoma. Colonic LS1 74T xenografts produced mucin and carcinoembryonic antigen (CEA). The anti-CEA IgG1 monoclonal antibody A5B7 was radiolabelled with iodine-131 and administered intravenously to sheep. Peak uptake at 5 days in orthotopic human tumour transplants in gut was 0.027% DI g(-1) (percentage of injected dose per gram) and 0.034% DI g(-1) in hepatic metastases with tumour to blood ratios of 2-2.5. Non-specific tumour uptake in melanoma was 0.003% DI g(-1). Uptake of radiolabelled monoclonal antibody in human tumours in our large animal model is comparable with that observed in patients and may be more realistic than nude mice xenografts for prediction of clinical efficacy of radioimmunotherapy.

Design and performance of a stable linear retarder

The National Institute of Standards and Technology (NIST) has developed a nominally quarter-wave linear retarder for wavelengths near 1.3 mum that is stable within +/-0.1 degrees retardance over a range of wavelength, input angle, temperature, and environmental variations. The device consists of two concatenated Fresnel rhombs made from a low stress-optic-coefficient glass that minimizes the residual birefringence from machining and packaging. Device machining, assembly, and antireflection coating tolerances are discussed, and the theoretical performance is compared with measurements. Humidity can modify retardance of the total-internal-reflection surfaces; we discuss packaging that mitigates this effect and provides an estimated 10-year lifetime for the device. Several measurement methods were intercompared to ensure that the device retardance can be measured with an uncertainty less than 0.1 degrees . Similar retarders will be certified by NIST and made available as Standard Reference Materials.

Rotating-polarizer polarimeter for accurate retardance measurement

We demonstrate an automated polarimeter based on a rotating polarizer for the measurement of linear retardance independent of laser power and detector gain. The retardance is found when a curve is fitted to a unique normalization of the intensity response of the polarimeter over a range of input polarizer orientations. The performance of this polarimeter is optimal for measurements of quarter-wave retardance and minimal for half-wave retardance. Uncertainties are demonstrated by measurements on six stable double Fresnel rhombs of nominal quarter-wave retardance, yielding expanded uncertainties between 0.031 degrees and 0.067 degrees . The accuracy has also been verified by blind comparisons with interferometric and modified null retardance measurement techniques.

Optical, thermo-optic, electro-optic, and photoelastic properties of bismuth germanate (Bi(4)Ge(3)O(12))

To assess the suitability of bismuth germanate as an electro-optic material for high precision applications, we have confirmed and extended previous data on its refractive index, electro-optic tensor element r(41), and thermal expansion coefficient. In addition, we have measured the thermo-optic coefficient dn/dT, the temperature dependence of the electro-optic coefficient, and the stress-optic tensor elements. From the stress-optic tensor elements and previously published data, we have computed the strain-optic tensor elements. The index of refraction is given, to a good approximation, by the single-term Sellmeier equation, n(2) - 1 = S(0)λ(0)(2)/[1 - (λ(0)/λ)(2)], with S(0) = 95.608 µm(-2) and λ(0) = 0.1807 µm. The thermo-optic coefficient is 3.9 × 10(-5)/°C at 632.8 nm and 3.5 × 10(-5)/°C at 1152.3 nm. The electro-optic tensor element varies between approximately 1.05 and 1.11 pm/V over the spectral range of 550-1000 nm; its normalized effective change with temperature is approximately 1.54 × 10(-4)/°C. The thermal expansion coefficient is 6.3 × 10(-6)/°C over the range 15-125 °C. Values of the stress-optic tensor elements are q(11) - q(12) = -2.995 × 10(-13) m(2)/N and q(44) = -0.1365 × 10(-12) m(2)/N. The strain-optic tensor elements are p(11) - p(12) = -0.0266 and p(44) = -0.0595.

Simultaneous laser-diode emission and detection for fiber-optic sensor applications

The simultaneous emission and detection of radiation with a semiconductor laser is investigated. Measured signal-to-noise ratios of up to 56 dB demonstrate that self-detecting devices are adequate for sensor applications with discrete measurands. We observed a strong polarization dependence, which can cause response fluctuations, and suggest methods to minimize these fluctuations. This technique could be used for lower-cost sensors without splitters and detectors.

Clonal analysis of lung and blood T cells in patients with sarcoidosis

BACKGROUND

Sarcoidosis is a disease characterised by clinical "anergy" to delayed type hypersensitivity antigens and the formation of non-caseating granulomas, which frequently manifests in the lungs as a T lymphocyte/mononuclear cell alveolitis. Although there is an increased proportion of T cells in bronchoalveolar lavage (BAL) samples from these patients, and these T cells often show evidence of activation and spontaneous secretion of cytokines such as interleukin 2 (IL-2) and interferon gamma (IFN gamma)--a pattern similar to delayed type hypersensitivity reactions--it is unclear whether both cytokines are produced by the majority of T cells derived from the lungs of patients with sarcoidosis or whether unique subpopulations of T cells produce each cytokine. In this study the properties of T cells cloned from BAL fluid samples of patients with sarcoidosis have been analysed.

METHODS

T cells were cloned by limiting dilution using IL-2, phytohaemagglutinin, and irradiated feeder cells. Cloning efficiencies were compared and phytohaemagglutinin induced clonal production of IL-2, IFN gamma, and IL-4 was determined by bioassay (IL-2 and IFN gamma) or ELISA (IL-4).

RESULTS

T cells derived from the BAL fluid of patients with sarcoidosis cloned less efficiently than those from blood of the same individuals. Lung derived clones (CD4+ or CD8+) produced IFN gamma more frequently and to a higher titre than blood derived clones, whereas IL-2 production by CD4+ clones derived from BAL fluid was less than that from blood derived clones. Interestingly, IL-4 production by clones from both sites was similar. Analysis of the co-production of IL-2, IFN gamma, and IL-4 by these BAL fluid clones did not demonstrate a predominant "Th1"-like population which has been suggested to underlie delayed type hypersensitivity reactions.

CONCLUSIONS

The reduced cloning efficiency of T cells from the lung compared with the blood in sarcoidosis is consistent with, although probably more pronounced than, previous observations in normal lungs and shows that T cell hyporesponsiveness is not overcome in the lungs of patients with sarcoidosis. Furthermore, major differences exist between the cytokine producing potential of T cells derived from the lung and the blood in sarcoidosis, and these parallel the differences in the properties of blood and lung T cells seen in healthy individuals.

An analysis of the relationship between gamma delta T cell receptor V gene usage and non-major histocompatibility complex-restricted cytotoxicity

gamma delta T cells are capable of mediating non-major histocompatibility complex (MHC) restricted lysis of a variety of tumour cell lines. The mechanism of this lysis and its significance in tumour immunity are not clear. We have used a panel of five malignant mesothelioma (MM) cell lines, as well as standard tumour targets K562 and Daudi, to investigate some of the factors which could be involved in non-MHC restricted cytotoxicity mediated by gamma delta T cells. Individual MM cell lines, representing a panel of lines derived from a single cell type, varied in their susceptibility to lysis by gamma delta T cell clones. Individual gamma delta T cell clones also showed unique cytotoxic profiles, and differed in their cytotoxic potential. T cell receptor (TCR) V gamma gene usage correlated with the ability of clones to lyse Daudi or K562; clones lysing Daudi expressing V gamma 9 and clones lysing K562 expressing V gamma I subgroup genes. No strict correlation between V gamma and V delta gene usage and MM reactivity was, however, demonstrable. There was also no correlation between gamma delta T cell lysis of MM cell lines and the capacity of gamma delta T cells to produce interferon-gamma, tumour necrosis factor-alpha, interleukin-2 or interleukin-4, nor with their expression of CD8.

Genetic 'risk' for atopy is associated with delayed postnatal maturation of T-cell competence

Recent in vitro studies suggest that IgE production in adults is co-ordinately regulated by negative signals from gamma IFN-producing CD4+ T-helper-1 (TH-1) and positive signals from IL-4 producing (TH-2) T-cells. Additionally, seroepidemiological evidence has pinpointed infancy as the period of maximum lifetime risk for T-cell sensitization to ubiquitous environmental antigens. The present study sought to elucidate the relationship between these observations, by examination of CD4+ T-cell function in normal children and those genetically at 'high risk' for atopy, spanning the age range (up to 4 years) in which IgE responses to environmental allergens is typically manifest. Immunocompetent T-cell precursor frequencies (determined by cloning at limiting dilution) were markedly reduced in 'high risk' children relative to normals (0.53 +/- 0.29 vs 0.26 +/- 0.19; P = 0.0025). Consistent with reports from other laboratories employing bulk T-cell culture techniques, the gamma IFN producing capacity of CD4+ T-cell clones from both groups of children were markedly reduced relative to adults, and was lowest in the high risk group (P < 0.02). IL-4 production by CD4+ T-cell clones from the normal children was within the adult range, but again was significantly lower in the high risk group (P < 0.00005). This indicates that initial immune responses to environmental allergens in early childhood occur against a background of maturational 'deficiency' in CD4+ T-cell function, and suggests the possibility that variations in the rate of postnatal maturation of T-cell competence may be a contributing factor in the development of differing patterns of immunological responsiveness to environmental allergens.

A clonal analysis of lung T cells derived by bronchoalveolar lavage of healthy individuals

The characteristics of the T-cell population in the healthy human lung have been investigated by analysing the properties of T-cell clones derived from bronchoalveolar lavage (BAL) samples and comparing them with T cells cloned from the blood of the same individuals. The proportions of CD4+ and CD8+ T cells in the starting populations from BAL and blood were similar although only 14% of BAL T cells were CD45RA+ compared to 70% of blood T cells. The precursor frequency of T-cell clones derived from BAL was less than from blood. The cytokine profiles [after phytohaemagglutinin (PHA) stimulation] of the clones derived from both sources were markedly different and these differences lay in the CD4+ population. BAL-derived CD4+ clones produced interferon-gamma (IFN-gamma) more frequently than did those from blood while blood-derived clones were more likely to produce interleukin-2 (IL-2) than those from BAL. IL-4 was produced by the majority of BAL- or blood-derived clones (93% and 88% respectively) either along with IFN-gamma (BAL) or IL-2 (blood). The cytokine profiles of BAL-derived T-cell clones are consistent with those derived from lung interstitium and suggest that the BAL T-cell populations reflect those in the lung wall. Whether the unique properties of lung T cells are acquired after leaving the blood or whether there is selective entry of T-cell subpopulations into the lung remains to be determined.

Incorporation of unsaturated fatty acids by Saccharomyces cerevisiae: conservation of fatty-acyl saturation in phosphatidylinositol

Saccharomyces cerevisiae was grown anaerobically in media supplemented with myristoleic 14:1(9c), palmitoleic 16:1(9c), oleic 18:1(9c), linoleic 18:2(9,12c), gamma-linolenic 18:3(9,12,15c) or eicosenoic 20:1(11c) acid. Cells from exponential-phase cultures contained approximately the same proportions of the major phospholipid classes, namely phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine, the greatest differences being detected in cells grown in the presence of 14:1(9c) or 20:1(11c) acids. The extent to which phospholipids from cells were enriched with residues of the exogenously supplied acid varied from 52% in cells grown in the presence of 14:1(9c) acid to 13% in cells grown in media supplemented with 20:1(11c) acid. Analysis of the fatty-acyl composition of the four major phospholipid classes revealed that the degree of unsaturation varied considerably in three of the classes, while phosphatidylinositol conserved a high degree of saturation. The possible significance of the latter finding in relation to the physiological role of phosphatidylinositol in the plasma membrane is discussed.

Temperature dependence of the Verdet constant in several diamagnetic glasses

Measured temperature dependences of the Verdet constants of SiO(2), SF-57, and BK-7 are approximately 10(-4)/K within 3-20% of Becquerel formula estimates.

Asbestos-induced release of a human alveolar macrophage-derived neutrophil chemotactic factor

Neutrophils accumulate in the alveoli of asbestos-exposed individuals. In determining whether asbestos fibers induce the release of neutrophil chemotactic factor (NCF) from human alveolar macrophages, alveolar macrophages (10(6) cell/mL) obtained by bronchoalveolar lavage from six non-asbestos-exposed control subjects were exposed to crocidolite (0.1 and 1 mg/mL), chrysotile (1 mg/mL), or medium alone for 4 h, and NCF activity was measured in the supernatants in a 48-well microchemotaxis chamber with polycarbonate membrane filters (pore size, 3 microns) and purified human neutrophils. Alveolar macrophages in medium alone released negligible amounts of NCF (4 +/- 1 neutrophils per high-power field [N/HPF]). When macrophages were exposed to crocidolite (0.1 and 1 mg/mL), significant NCF release occurred (43 +/- 9 and 105 +/- 32 N/HPF, respectively; p less than 0.01 for each amount compare to alveolar macrophages cultured in medium alone). Chrysotile (1 mg/mL) induced similar NCF release (96 +/- 14 N/HPF; p less than 0.01 compared to unstimulated alveolar macrophages). Partial characterization of the NCF by Sephadex G-25 fine gel filtration demonstrated a molecular size of less than 1,000 daltons. These results show that human alveolar macrophages release NCF after exposure to asbestos. Release of NCF by alveolar macrophages in asbestos-exposed individuals may play a central role in the pathogenesis of asbestosis.

Pulmonary gamma interferon production in patients with fibrosing alveolitis

Patients with fibrosing alveolitis have active inflammation within their lung interstitium. Previous studies have focused on the humoral (immune complex) driven processes. In this study increased pulmonary gamma interferon production has been evaluated. Bronchoalveolar lavage cells were obtained from 40 patients with fibrosing alveolitis, 22 with cryptogenic fibrosing alveolitis, and 18 with connective tissue disease associated (CTD) fibrosing alveolitis. Increased gamma interferon production was seen in 12 (30%) patients and was similar in the two study groups. Up to 512 units/10(6) cells were released over 24 hours, showing that the amounts of gamma interferon released could be as large as those seen in other pulmonary diseases associated with active cellular immune processes, such as sarcoidosis. Spontaneous gamma interferon production was related to increased serum concentrations of IgG and IgM but not to serum IgA, antinuclear antibody, or rheumatoid factor titres. There was no relation between gamma interferon production and pulmonary uptake of gallium-67 citrate. The ratio of helper-inducer (Leu-3) to suppressor-cytotoxic (Leu-2) cells in bronchoalveolar lavage fluid was similar in the two study groups and was similar in patients whose cells produced gamma interferon and those whose cells did not. These data suggest that gamma interferon is released in the lungs of a proportion of individuals with cryptogenic fibrosing alveolitis and CTD-fibrosing alveolitis, suggesting a role for this cytokine in mediating these diseases.

Accumulation of sulphite by Saccharomyces cerevisiae and Zygosaccharomyces bailii as affected by phospholipid fatty-acyl unsaturation and chain length

Analyses were made of the fatty-acyl composition of phospholipids from each of two strains of Saccharomyces cerevisiae and Zygosaccharomyces bailii grown aerobically. Residues of C16:0, C16:1 and C18:1 predominated in phospholipids from strains of the first yeast, while phospholipids from Z. bailii contained mainly C16:0, C18:1 and C18:2 residues. S. cerevisiae NCYC 431, grown anaerobically in media supplemented with ergosterol and C14:1, C16:1, C18:1, C18:2, C18:3 or C20:1 fatty acids, contained phospholipids enriched with residues of the exogenously provided acid, to a greater extent with shorter chain than longer chain acids. A plot of the permeability coefficient for sulphite, derived from Woolf-Eadie plots, against the degree of unsaturation in phospholipids (expressed as delta mol-1 value) showed that the coefficient was greater the lower the degree of unsaturation in the phospholipids. A plot of the permeability coefficient against values for the mean fatty-acyl chain length divided by the delta mol-1 value, which is an approximation of the cross-section surface area of a phospholipid molecule, showed that the permeability coefficient tended to increase the greater the surface-area value.

Gallium lung scanning and bronchoalveolar lavage in crocidolite-exposed workers

Gallium lung scanning is widely used to evaluate pulmonary inflammation in patients with interstitial lung disease but has not previously been reported in crocidolite-exposed workers. In order to characterize the pulmonary inflammation caused by crocidolite inhalation, GLS and BAL findings were related to chest x-ray film changes graded according to the ILO classification of roentgenograms of pneumoconioses. In individuals with roentgenographic evidence of asbestosis (CXR greater than or equal to 1/0, n = 15), 13 had a positive GLS and 13 had an abnormal BAL. In asbestos-exposed individuals with equivocal chest x-ray film changes (CXR 0/1, n = 12), six had a positive GLS and six had BAL changes (both GLS and BAL abnormal in three). In individuals with a normal chest x-ray film (CXR 0/0 n = 8), two had a positive GLS and two BAL changes (both abnormal in 1). These data demonstrate that most subjects with crocidolite-induced asbestosis have an abnormal GLS and BAL. In addition, many individuals with asbestos exposure and equivocal or no chest x-ray film changes have an abnormal GLS and/or BAL, suggesting the presence of active subclinical pulmonary inflammation in these individuals.

Long-chain alcohol production by yeasts

Fourteen yeast strains from six genera were analysed for the presence of long-chain alcohols, the highest levels being found in Candida albicans. The major alcohols synthesized were saturated, primary alcohols with C14, C16 or C18 chain length with relative proportions of C16 greater than C18 greater than C14. In C. albicans synthesis of long-chain alcohols occurred only after the end of exponential growth. Long-chain alcohol contents were lower in organisms grown aerobically as compared with anaerobically and contents of all three classes increased as the concentration of glucose was raised from 1.0 to 30.0% (w/v). In anaerobic cultures greatest alcohol contents were obtained using medium containing 10% (w/v) glucose. Substituting glucose (10%, w/v) with the same concentration of galactose in aerobic cultures greatly decreased contents of long-chain alcohols, while inclusion of 10% (w/v) glycerol virtually abolished their synthesis. Supplementing anaerobic cultures with odd-chain fatty acids induced synthesis of odd-chain alcohols, Nitrogen limitation induced long-chain alcohol synthesis in aerobically grown Candida maltosa and quantities were increased with conditions of glucose excess and nitrogen limitation.

Sterol uptake by anaerobically grown Saccharomyces cerevisiae

Wild-type Saccharomyces cerevisiae Y185 grown anaerobically was used to investigate the uptake and subsequent utilisation of sterol in S. cerevisiae. Results confirmed a minimum free sterol concentration below which growth was retarded. The yeast does, however, appear capable of taking up sterol well in excess of that required for growth. Evidence is presented indicating the ability of the yeast cell wall to bind cholesterol both in vivo and with isolated cell walls. There appears to be a role for low density vesicles in the movement of sterol once within the cell.

Reactions of Saccharomyces cerevisiae and Zygosaccharomyces bailii to sulphite

Sulphite inhibited growth of all four yeasts studied, Zygosaccharomyces bailii NCYC 563 being most sensitive and Saccharomyces cerevisiae NCYC 431 the least. Vertical Woolf-Eadie plots were obtained for initial velocities of 35S accumulation by all four yeasts suspended in high concentrations of sulphite. Equilibrium levels of 35S accumulation were reached somewhat faster with strains of S. cerevisiae than with those of Z. bailii. With all four yeasts, the greater the extent of 35S accumulation, the larger was the decline in internal pH value. Growth of S. cerevisiae TC8 and Z. bailii NCYC 563, but to a lesser extent of S. cerevisiae NCYC 431 and Z. bailii NCYC 1427, was inhibited when mid exponential-phase cultures were supplemented with 1.0 or 2.0 mM-sulphite, the decrease in growth being accompanied by a decline in ethanol production. Unless growth was completely inhibited, the sulphite-induced decline in growth was accompanied by production of acetaldehyde and additional glycerol.

Neutrophil chemotactic factor release and neutrophil alveolitis in asbestos-exposed individuals

Alveolar neutrophil accumulation occurs in asbestosis. To evaluate a possible role for release of neutrophil chemotactic factor (NCF) in the pathogenesis of asbestosis, spontaneous NCF release from alveolar macrophages obtained by bronchoalveolar lavage (BAL) in eight individuals with asbestosis, 13 asbestos-exposed individuals without asbestosis, and five control subjects has been studied. Alveolar macrophages were incubated in medium (four hours; 37 degrees C), and neutrophil responses to the supernatants were assayed in a microchemotaxis chamber. Alveolar macrophages from subjects with asbestosis released more NCF (97 +/- 19 neutrophils per high-power field [N/HPF]) than controls (3 +/- 1 N/HPF; p less than 0.01). Alveolar macrophages from individuals with asbestos exposure and increased BAL neutrophil proportions (n = 7) released more NCF (93 +/- 24 N/HPF) than individuals with asbestos exposure and normal BAL neutrophil proportions (n = 6; 11 +/- 6 N/HPF; p less than 0.02). The results show that spontaneous NCF release occurs in asbestosis and that NCF release is associated with neutrophil alveolitis in asbestos-exposed individuals without asbestosis, suggesting a pathogenic role for NCF in mediating this neutrophil alveolitis. The results of the study also suggest that the presence of crackles is a better predictor of the presence of neutrophil alveolitis than is an abnormal chest x-ray film.

Effect of glucose and long-chain fatty acids on synthesis of long-chain alcohols by Candida albicans

Candida albicans, grown aerobically in glucose-containing media, produced C14, C16 and C18 saturated long-chain alcohols only after the end of exponential growth. Contents of C14 alcohols were always lowest, and C16 and C18 alcohol contents about equal. Contents of all three classes of alcohol increased as the concentration of glucose in aerobic cultures harvested after 168 h incubation was raised from 1.0 to 30.0% (w/v). However, in 168 h anaerobic cultures, greatest long-chain alcohol contents in organisms were obtained using media containing 10% (w/v) glucose. Substituting glucose (10%, w/v) with the same concentration of galactose in aerobic cultures greatly decreased contents of long-chain alcohols, while inclusion of 10% (w/v) glycerol virtually abolished their synthesis. Supplementing anaerobic cultures with odd-chain fatty acids induced synthesis of odd-chain alcohols. Maximum conversion of fatty acid to the corresponding long-chain alcohol was observed with heptadecanoic acid. The effect of glucose on production of heptadecanol from exogenously provided heptadecanoic acid was similar to that observed on synthesis of the three major even-chain alcohols in media lacking a fatty-acid supplement. Cell-free extracts of organisms catalysed in vitro conversion of palmitoyl-CoA to 1-hexadecanol.

Increased pulmonary gamma interferon production in asbestosis

In order to determine if disordered cellular immune processes are present in the lungs of persons with asbestosis, we performed bronchoalveolar lavage (BAL) on 26 patients with either crocidolite- or chrysotile-induced pulmonary asbestosis and measured the spontaneous release of gamma interferon (IFN gamma), a marker of increased cellular immune activity. For comparison, 18 control subjects and 7 patients with active pulmonary sarcoidosis were also studied. Recovered BAL cells were cultured for 24 h (5 x 10(6)/ml), and the supernatant was assayed for interferon by determining inhibition of cytopathic effect on encephalomyocarditis virus-induced lysis of WISH cells and characterized by monoclonal anti-IFN gamma antibody inhibition. Nine (35%) patients with asbestosis released increased amounts of IFN gamma, up to 320 units/ml, the levels seen in the sarcoidosis patients. All control subjects released less than or equal to 10 units/ml. All interferon released was IFN gamma. In asbestosis patients, IFN gamma production was not related to a history of cigarette smoking, there was no significant difference in the ratio of helper/inducer (Leu-3) to suppressor/cytotoxic (Leu-2) cells in IFN gamma producers compared to non-IFN gamma producers (p greater than 0.05), and IFN gamma production correlated significantly with serum IgG levels (p less than 0.001) but not with the levels of IgM, IgA, antinuclear factor, or rheumatoid factor. These data suggest that active cellular immune processes are present in the lungs of a proportion of patients with asbestosis.

Bronchoalveolar lavage sampling of airway and alveolar cells

Bronchoalveolar lavage (BAL) cell counts are used to assess 'alveolitis' in patients with interstitial lung diseases (ILD) but inflammatory cells from airways can contribute to the differential cell count. To determine what BAL volume samples airway cells in patients with ILD we measured the proportion of bronchial epithelial cells (BECs) in four successive 25 ml aliquots in a single lung subsegment in 23 patients with ILD (cryptogenic fibrosing alveolitis (CFA) four, rheumatoid lung (RL) three, asbestosis (ASB) 11, sarcoidosis (SARC) five). Cells recovered from the first two 25 ml lavages exhibited higher proportions of BECs (15 +/- 4% and 9 +/- 2% respectively) than those from the remaining two aliquots (3 +/- 1%, 3 +/- 1%, each P less than 0.01), suggesting that the first 50 ml BAL preferentially samples airway cells compared to the second 50 ml BAL. To evaluate airway and alveolar inflammatory cell proportions in ILD we performed two separate 50 ml BALs (samples I and II) in a single subsegment in 38 patients with ILD (CFA seven, RL five, ASB 19, SARC seven) and measured the proportions of recovered cells in each sample separately and combined. Seven control individuals were also studied. Sample I contained 1-67% (mean 26 +/- 3%) of the total recovered cells. Neutrophil (PMN) proportions were higher in sample I compared to sample II in CFA (20 +/- 6 vs 8 +/- 2%), RL (30 +/- 9 vs 8 +/- 2%) and ASB (12 +/- 2 vs 7 +/- 1%), P less than 0.05 for each, but were similar in samples I and II in patients with SARC (3 +/- 1 vs 2 +/- 1%) and controls (2 +/- 1 vs 2 +/- 1%). In combined samples (I + II), absolute PMN proportions were up to 8% higher than in sample II alone whereas absolute lymphocyte proportions were up to 8% less than in sample II alone. These data suggest that separate processing of the fluid recovered from the first 50 ml BAL in ILD patients provides information on the location of inflammatory cells and improves the accuracy of BAL cell counts.

Production of long-chain alcohols by yeasts

Fourteen yeast strains from six genera were analysed for the presence of long-chain alcohols. Six strains from three genera contained long-chain alcohols, highest levels being found in Candida albicans. The alcohols were identified and determined by TLC, GLC and GLC-MS. The major long-chain alcohols synthesized by these organisms were saturated, primary alcohols with C14, C16 or C18 chain length. Unsaturated long-chain alcohols were not detected. In all strains that produced long-chain alcohols, the relative proportions were C16 greater than C18 greater than C14. Long-chain alcohol contents were higher in organisms from anaerobically, as compared with aerobically, grown cultures reaching about 650 micrograms (g dry wt organisms)-1 in stationary-phase cultures of C. albicans. In cultures of C. albicans, synthesis of long-chain alcohols occurred only after the end of exponential growth. The alcohols were predominantly present as free alcohols. The fatty-acyl chain-length profile of the triacylglycerol and to a lesser extent the sterol/wax ester fractions from C. albicans reflected that of the long-chain alcohols produced by this yeast.

Effect of ethanol on activity of the plasma-membrane ATPase in, and accumulation of glycine by, Saccharomyces cerevisiae

The pH optimum of the ATPase activity in plasma membranes from Saccharomyces cerevisiae NCYC 431 from 8 h cultures was around 6.5 and that in membranes from organisms from 16 h cultures near 6.0. The Km[ATP] of the enzyme was virtually unaffected by the age of the culture from which organisms were harvested, although the Vmax of the enzyme in membranes from organisms from 8 h cultures was higher than that for organisms from 16 h cultures. Ethanol non-competitively inhibited ATPase activity in membranes, although the inhibition constant for the enzyme from organisms from 8 h cultures was lower than that from organisms from 16 h cultures. Glycine accumulation by the general amino acid permease was non-competitively inhibited by ethanol. Inhibition constants were virtually the same for glycine uptake by deenergized organisms from 8 h and 16 h cultures, but under energized conditions the value was greater for organisms from 16 h rather than 8 h cultures. The data indicate that inhibition of plasma-membrane ATPase activity by ethanol could account, at least in part, for inhibition of glycine accumulation by ethanol.

Comparison of bronchoalveolar lavage helper/suppressor T-cell ratios in sarcoidosis versus other interstitial lung diseases

In order to compare the frequency of elevated lymphocyte proportions and elevated Leu3/Leu2 (helper/inducer to suppressor/cytotoxic) ratios in sarcoidosis with those in clinically similar interstitial lung diseases (ILDs), bronchoalveolar lavage (BAL) lymphocyte proportions and Leu3/Leu2 ratios were determined for 20 patients with sarcoidosis and 30 patients with other (non-sarcoidosis) ILDs [cryptogenic fibrosing alveolitis (seven), lung connective tissue disease (seven), extrinsic allergic alveolitis (four), lymphoproliferative disease (two), and asbestosis (ten)], as well as in eight control subjects. BAL lymphocyte proportions were elevated above control values in 19 (95%) patients with pulmonary sarcoidosis (mean value 36 +/- 3%) but also in 12 (39%) patients with non-sarcoidosis ILDs (mean value 17 +/- 4%). Leu3/Leu2 ratios were over 2.5 in 15 (75%) of the sarcoidosis patients (mean ratio 4.4 +/- 1). In all control subjects, however, and in all but one of the non-sarcoidosis groups, Leu3/Leu2 ratios were below 2.5 (p less than 0.001 for each compared to sarcoidosis patients). Helper/suppressor ratios over 2.5 are found in the majority of our sarcoidosis patients and, unlike raised lymphocyte proportions alone, are not commonly seen in other ILDs, suggesting that evaluation of BAL helper/suppressor cell ratios may be of value in the investigation of patients with ILD.

Alveolitis of pulmonary asbestosis. Bronchoalveolar lavage studies in crocidolite- and chrysotile-exposed individuals

Bronchoalveolar lavage (BAL) findings in 27 individuals with crocidolite- or chrysotile-induced asbestosis were compared to BAL findings in 29 unexposed control subjects. Alveolitis, defined as an increase in the proportions and/or absolute numbers of inflammatory cells present in BAL fluid compared to values in control subjects, was present in 26 (96 percent) subjects with asbestosis. Most exhibited a neutrophil-eosinophil alveolitis, with neutrophil proportions increased to 7.4 +/- 0.7 percent and eosinophil proportions increased to 2.2 +/- 0.4 percent, compared to 2 +/- 0.5 percent and 0.4 +/- 0.01 percent, respectively, in control subjects (p less than 0.01 for both neutrophils and eosinophils). An increase in the total number of neutrophils and eosinophils per ml of lavage fluid was also seen (neutrophils 23 +/- 5 and eosinophils 13 +/- 4 per ml; p less than 0.05 compared to control subjects). Severity of the alveolitis, defined by the neutrophil or eosinophil proportions, was independent of a history of exposure to cigarette smoke. The pattern and severity of alveolitis in crocidolite- and chrysotile-induced asbestosis were similar. There was a significant correlation between duration of exposure to asbestos and neutrophil proportions (p less than 0.01). No significant difference in the severity of the alveolitis was observed between individuals with radiologic and physiologic evidence of asbestosis compared to those with asbestos exposure and crackles alone, suggesting that, in asbestosis as in other chronic interstitial lung diseases, radiologic and physiologic parameters do not reflect the severity of the alveolitis. This study demonstrates that a neutrophil-eosinophil alveolitis is present in individuals with crocidolite- and chrysotile-induced asbestosis, that this alveolitis is independent of cigarette smoking, and that the severity of the BAL changes is not reflected in radiologic and physiologic changes.

Plasma-membrane phospholipid unsaturation affects expression of the general amino-acid permease in Saccharomyces cerevisiae Y185

Saccharomyces cerevisiae Y185, enriched in linoleyl residues and incubated for up to 4 h in derepression buffer, more rapidly acquired general amino-acid permease (GAP) activity, as measured by the rate of accumulation of L-alanine, compared with organisms enriched in oleyl residues. A GAP-less mutant incubated under the same conditions did not acquire further L-alanine-accumulating ability, irrespective of the nature of the fatty-acyl enrichment. During derepression, KT values for the GAP were virtually identical irrespective of the fatty-acyl enrichment, but Vmax values were greater for linoleyl residue-enriched organisms, particularly after 1 h in derepression buffer. During incubation in derepression buffer, organisms with either fatty-acyl enrichment did not differ in the size of the amino-N pool, the concentration of L-alanine in that pool, rates of protein synthesis and glucose fermentation, or rate and extent of incorporation of label from H2 32PO-4. Under conditions used to measure rates of L-alanine accumulation, organisms with either enrichment showed no evidence of metabolism of accumulated L-alanine.

IgE responses of malnourished mice: immunogenic and tolerogenic effects of low-grade antigenic stimulation

Mice maintained on protein-restricted diets after weaning manifested normal IgE (and IgG) responses following intraperitoneal immunization under conditions of maximal antigenic stimulation, i.e., antigen adsorbed to adjuvant. However, antigenic challenge at levels closer to the stimulation threshold, employing soluble antigen alone, revealed marked differences between the immune competence of normal and malnourished animals. Diminished IgE responsiveness to soluble antigen in the malnourished mice was accompanied by enhanced susceptibility to the induction of antigen-specific tolerance associated with the appearance of suppressor T cells in the spleen. It is argued that enhanced susceptibility to suppressor T-cell induction under conditions of minimal antigenic stimulation may underlie the diminished IgE responsiveness of the malnourished animals.

The effect of a low protein diet on the immunogenic activity of murine peritoneal macrophages

The activity of resident and exudate peritoneal macrophages from mice maintained on a low protein diet (4% casein initiated at weaning) was assessed in a variety of assay systems which examined aspects of macrophage 'immunogenic' function in vivo and in vitro. Antigen-pulsed macrophages from malnourished mice triggered secondary IgE and IgG responses following intraperitoneal inoculation into pre-immunized syngeneic recipients. Similarly, intraperitoneal transfer of low numbers of these cells successfully primed immunologically naive syngeneic mice; in both cases, the activity of macrophages from malnourished mice could not be distinguished from these derived from normal animals. Examination of uptake and breakdown of radio-labelled antigen revealed normal rates of phagocytosis, and a brief lag in the early phase of degradation, relative to control macrophages. Antigen-pulsed macrophages from malnourished mice were severely impaired in their capacity to trigger the proliferation of antigen-primed T cells in vitro.

Induction of adjuvant-independent IgE responses in inbred mice: primary, secondary, and persistent IgE responses to ovalbumin and ovomucoid

Immunization of a number of inbred mouse strains intraperitoneally with low levels (1-100 micrograms) of ovalbumin (OA) or ovomucoid (OM) in the absence of adjuvant, revealed marked strain differences in IgE responsiveness. High-OA-responder strains such as Balb/c exhibited PCA titre up to 256 in the primary response, and up to 1,280 in the secondary, while non-responders such as SJL and NZB remained PCA negative; similar variations were found in the response of the strains to OM. Repeated immunization of high-OA-responder mice with low doses of antigen without adjuvant elicited anamnestic second and tertiary HA antibody responses. In contrast, IgE responses exhibited anamnestic secondary responses, but were not further boosted by tertiary stimulation. Instead, a 'persistent' high IgE response of the type previously associated with the use of specialized adjuvants, developed in these mice. Fractionation of the OA antigen by gel filtration yielded molecular species (dimers pentamers) of considerably greater IgE-immunogenicity than either monomeric OA or very highly aggregated forms. Immunization of high-OA-responder mice with the former permitted lowering of the threshold for induction of adjuvant-independent primary OA-IgE responses to a single 1.0 microgram dose, and the threshold for priming to 0.1 microgram.

Effect of a low protein diet on IgE antibody responses in Balb/c mice

Mice maintained on a low protein diet (4% casein initiated at weaning) produced IgE antibody responses to both ovalbumin and Ascaris body fluid proteins. The titres in young mice were comparable to those of mice maintained on a normal (20% protein) diet particularly at high doses of immunogen. However, following immunization with low doses of immunogen the initiation of antibody response in malnourished mice was delayed and the levels finally obtained were significantly suppressed below normal levels. This effect was more apparent in animals maintained for prolonged periods on diet. Possible mechanisms for this suppression are presented.

Scanning electron microscope study of Saccharomyces cerevisiae spheroplast formation

A suspension of Saccharomyces cerevisiae NCY366 in buffered 1.2 M sorbitol containing Zymolyase-5000 (a beta-glucanase-containing preparation/showed maximum osmotic sensitivity after 30 min of incubation at 30 degrees C. A scanning electron microscope study of spheroplast formation, using a very high resolution (4-nm) machine, revealed several new morphological features. The surface of the plug in bud scars on intact cells appeared warty. The wall, which assumed a beady appearance as digestion proceded, ultimately sloughed off to reveal the furrowed surface of the plasma membrane. Bud scars were resistant to digestion and. as incubation proceeded, they became surrounded by an outer annulus, which may be the seconary septum. Wall material was completely removed from the majority of cells only after 60 min of digestion. The surface of spheroplasts was studded with particles, about 25 to 30 nm in diameter. Many spheroplasts had a single large indentation, which may be in that part of the plasma membrane originally underlying the birth scar.