The Concept of Microwave Foam Drying Under Vacuum: A Gentle Preservation Method for Sensitive Biological Material

Microwave vacuum drying as compared to conventional vacuum drying has evinced advantages regarding drying time, while comparable product characteristics were achieved when drying sensitive biological material. Due to the volumetric microwave input, a time reduction of up to 90% is possible. When drying viscous liquids, a foamed structure that remains stable during drying exhibits further advantages as the diffusion-limited third drying step is enhanced by the porous structure. As foams not only have to be thermally resistant during microwave vacuum processing, but also withstand the vacuum, a specific process for foam drying by microwaves under low pressure conditions was developed. Foam formation and stabilization was achieved by using a synergistic mixture of proteins and carbohydrates; Lactobacillus paracasei ssp. paracasei F19 (L. paracasei) served as a model sensitive substance. Investigation of surface activity and foaming properties as a function of L. paracasei concentration revealed a significant positive contribution of the bacterial cells. It was shown that L. paracasei directly adsorbed at the air-water interface. Besides, a structuring of the liquid lamellae was assumed. Moreover, drying time was reduced to at least 50% compared to microwave vacuum drying without foaming. It was further observed that the slight loss in survival was mainly due to the relatively high moisture content and high vacuum levels at the beginning of the process. However, foaming, vacuum application, and final drying, respectively, did not affect viability of the bacterial cells. Thus, by incorporation of lactic acid bacteria into foam structures, drying can be carried out in a fraction of time, and further results in high-product quality. PRACTICAL APPLICATION: The application of continuous foam drying offers an efficient and energy-saving alternative to the currently applied techniques for the processing of sensitive material. The process could be applied for the preservation of starter cultures and probiotics as well as in the pharmaceutical industry, when sensitive material such as therapeutic proteins is dried. This process is especially suitable for freezing-sensitive and thermolabile substances.

Clinical performance of the Solana® Point-of-Care Trichomonas Assay from clinician-collected vaginal swabs and urine specimens from symptomatic and asymptomatic women

BACKGROUND

Solana® (Quidel) is a new rapid (<40 min.) point-of-care (POC) test for qualitative detection of Trichomonas vaginalis (TV) DNA. The assay has two steps: 1) specimen preparation, and 2) amplification and detection using isothermal Helicase-Dependent Amplification (HDA). The objective was to demonstrate the performance of Solana for vaginal swabs and female urines based on comparison to wet mount and TV culture. Performance was also compared to the Aptima-TV assay.

METHODS

Urine and four clinician-collected vaginal swabs were collected. The first two were used for FDA composite reference (wet mount; InPouch TV Culture). The third swab was used for Solana. Sensitivity/specificity were based on the reference method. A specimen was considered positive if either test was positive. The fourth swab was for Aptima-TV.

RESULTS

Vaginal swabs and urines were obtained from 501 asymptomatic and 543 symptomatic women. Prevalence of TV by was 11.5%. For swabs, Solana® demonstrated high sensitivity and specificity from asymptomatic (100%/98.9%) and symptomatic (98.6%/98.5%) women, as well as for urines from asymptomatic (98.0%/98.4%) and symptomatic (92.9%/97.9%) women, compared to the reference method. Compared to Aptima-TV, the sensitivity/specificity was 89.7%/99.0% for swabs and 100%/98.9% for urines.

CONCLUSION

The Solana® assay performed well compared to the reference assays.

Rat cardiovascular responses to whole body suspension: head-down and non-head-down tilt

The rat whole body suspension technique mimics responses seen during exposure to microgravity and was evaluated as a model for cardiovascular responses with two series of experiments. In one series, changes were monitored in chronically catheterized rats during 7 days of head-down tilt (HDT) or non-head-down tilt (N-HDT) and after several hours of recovery. Elevations of mean arterial (MAP), systolic, and diastolic pressures of approximately 20% (P < 0.05) in HDT rats began as early as day 1 and were maintained for the duration of suspension. Pulse pressures were relatively unaffected, but heart rates were elevated approximately 10%. During postsuspension (2-7 h), most cardiovascular parameters returned to presuspension levels. N-HDT rats exhibited elevations chiefly on days 3 and 7. In the second series, blood pressure was monitored in 1- and 3-day HDT and N-HDT rats to evaluate responses to rapid head-up tilt. MAP, systolic and diastolic pressures, and HR were elevated (P < 0.05) in HDT and N-HDT rats during head-up tilt after 1 day of suspension, while pulse pressures remained unchanged. HDT rats exhibited elevated pretilt MAP and failed to respond to rapid head-up tilt with further increase of MAP on day 3, indicating some degree of deconditioning. The whole body suspended rat may be useful as a model to better understand responses of rats exposed to microgravity.

Biochemical and immunological characterization of the major structural proteins of feline immunodeficiency virus

Feline immunodeficiency virus (FIV) structural proteins were identified using sera obtained from experimentally inoculated cats. Proteins analysed by both radioimmunoprecipitation and Western blotting were specific for FIV infection and failed to cross-react with either antisera to feline leukaemia virus of feline syncytium-forming virus. Western blot analysis of purified virus revealed immunoreactive proteins with apparent Mr of 65K, 50K, 40K, 32K, 24K, 15K and 10K. The major core structural proteins of the virus were isolated by reverse phase HPLC and the aminoterminal sequences of p10 and p24 were determined. Monoclonal antibodies specific for p24 suggested the presence of a precursor protein that could be detected in 35[S]methionine/cysteine-labelled, virus-infected cell extracts. This putative precursor protein possessed an apparent Mr of 50K (Pr50gag). Further analysis revealed the presence of two additional proteins of 130K and 40K. Experiments utilizing tunicamycin, endoglycosidase H and glycopeptidase F revealed that p130 and p40 exhibited properties characteristic of glycoproteins. Our studies also indicated that FIV is immunologically related to other lentiviruses.

Immunosuppression during viral oncogenesis. V. Resistance to virus-induced immunosuppressive factor

Rabbits given malignant rabbit fibroma virus (MV) develop severe immunologic dysfunction during the course of infection. Splenic T lymphocytes from these rabbits elaborate a soluble non-specific immunosuppressive factor (virus-induced suppressor factor (VISF]. As malignant rabbit fibroma virus infection progresses, normal immunologic responsiveness returns. This recovery is multi-factorial and involves production by T lymphocytes of a soluble factor capable of antagonizing the activity of VISF. This soluble anti-suppressor factor (ASF) is not a generalized immunologic potentiator. Its sole apparent effect on immune function appears to be to antagonize the activity of VISF. The protective effects of ASF are evident only when suppressor factors and ASF are simultaneously present in culture. Pre-treatment of target cells with ASF-containing culture supernatants does not render them insensitive to the immunosuppressive effects of subsequent treatment with VISF. In addition, ASF appears to be directly responsible for antagonizing VISF activity. That is, ASF does not appear to initiate an anti-suppressive cascade by activating a population of cells that in turn generate secondary protective factors. ASF-producing cells do not bind Vicia villosa lectin, as do contra-suppressor cells described by others. In almost all of these features, the system we describe herein differs from systems in which other investigators have described factors that antagonize the effects of suppressor factors.

Immunosuppression during viral oncogenesis. V. Resistance to virus-induced immunosuppressive factor

Rabbits given malignant rabbit fibroma virus (MV) develop severe immunologic dysfunction during the course of infection. Splenic T lymphocytes from these rabbits elaborate a soluble non-specific immunosuppressive factor (virus-induced suppressor factor (VISF]. As malignant rabbit fibroma virus infection progresses, normal immunologic responsiveness returns. This recovery is multi-factorial and involves production by T lymphocytes of a soluble factor capable of antagonizing the activity of VISF. This soluble anti-suppressor factor (ASF) is not a generalized immunologic potentiator. Its sole apparent effect on immune function appears to be to antagonize the activity of VISF. The protective effects of ASF are evident only when suppressor factors and ASF are simultaneously present in culture. Pre-treatment of target cells with ASF-containing culture supernatants does not render them insensitive to the immunosuppressive effects of subsequent treatment with VISF. In addition, ASF appears to be directly responsible for antagonizing VISF activity. That is, ASF does not appear to initiate an anti-suppressive cascade by activating a population of cells that in turn generate secondary protective factors. ASF-producing cells do not bind Vicia villosa lectin, as do contra-suppressor cells described by others. In almost all of these features, the system we describe herein differs from systems in which other investigators have described factors that antagonize the effects of suppressor factors.

Immunosuppression during viral oncogenesis. IV. Generation of soluble virus-induced immunologic suppressor molecules

We describe herein functional attributes and generation of immunologic suppressor activity elaborated in response to oncogenic virus infection. Malignant rabbit fibroma virus-induced immunologic suppressor factor (VISF) is a T cell product produced in peak quantities by spleen cells taken from infected rabbits 7 days after infection in vivo. Its production does not appear to require macrophage participation. VISF is highly labile, 3.5 to 12 kDa, and capable of suppressing both B and T lymphocytic responses. Indomethacin and the cyclic nucleotides cAMP and cGMP inhibit its generation. VISF activity is neither antigen nor species specific. It suppresses murine and leporine immune responses to antigens unrelated to the inducing virus. Comparable suppressor activity may be induced by infecting an apparently non-functional rabbit T lymphoma line, RL-5, with malignant rabbit fibroma virus. VISF is principally a suppressor-inducer factor: in vitro, lymphocytes exposed to VISF do not show decreased immunologic responsiveness until 4 days of culture. VISF induces T suppressor cell activity when normal spleen cells are exposed briefly to VISF. Thus, immunosuppressive consequences of malignant fibroma virus infection are partially mediated by a small, non-specific T cell-derived suppressor lymphokine with unique functional characteristics. Non-specific immunologic dysfunction that often attends virus infections may reflect the activity of such factors in humans as well.

Immunosuppression during viral oncogenesis. IV. Generation of soluble virus-induced immunologic suppressor molecules

We describe herein functional attributes and generation of immunologic suppressor activity elaborated in response to oncogenic virus infection. Malignant rabbit fibroma virus-induced immunologic suppressor factor (VISF) is a T cell product produced in peak quantities by spleen cells taken from infected rabbits 7 days after infection in vivo. Its production does not appear to require macrophage participation. VISF is highly labile, 3.5 to 12 kDa, and capable of suppressing both B and T lymphocytic responses. Indomethacin and the cyclic nucleotides cAMP and cGMP inhibit its generation. VISF activity is neither antigen nor species specific. It suppresses murine and leporine immune responses to antigens unrelated to the inducing virus. Comparable suppressor activity may be induced by infecting an apparently non-functional rabbit T lymphoma line, RL-5, with malignant rabbit fibroma virus. VISF is principally a suppressor-inducer factor: in vitro, lymphocytes exposed to VISF do not show decreased immunologic responsiveness until 4 days of culture. VISF induces T suppressor cell activity when normal spleen cells are exposed briefly to VISF. Thus, immunosuppressive consequences of malignant fibroma virus infection are partially mediated by a small, non-specific T cell-derived suppressor lymphokine with unique functional characteristics. Non-specific immunologic dysfunction that often attends virus infections may reflect the activity of such factors in humans as well.

Growth of malignant rabbit fibroma virus in lymphoid cells

To understand better the immunosuppressive capacity of malignant rabbit fibroma virus (MV), we characterized MV growth in lymphoid cells. Replication of MV occurs in unstimulated normal spleen cells in vitro and is enhanced by adding T- or B-lymphocyte mitogens. In splenic T-lymphocyte preparations, comparable results are found: virus growth in the absence of mitogen, augmented by adding Con A. Unlike mature T cells, thymic lymphocytes support MV replication only when mitogen is added. When spleen cells from rabbits infected with MV in vivo are removed and cultured without mitogen, MV growth is again observed, with virus titer increasing about 10-fold per day of culture. In spleen cell populations from MV tumor-bearing rabbits, MV grows best in T lymphocytes, moderately in B lymphocytes, and least efficiently in adherent cells. When spleen cells are examined immediately following sacrifice, MV antigens are expressed solely on T lymphocytes from rabbits infected in vivo with MV 7 days previously. However, following overnight incubation in vitro a population of non-T lymphocytes displays cell membrane virus antigens. MV adapts itself somewhat to growth in lymphocytes, showing significantly greater growth in lymphocytes following passage in lymphocytes than is observed for non-lymphocyte-propagated virus. MV-infected lymphocytes also elaborate a factor that enhances MV growth in lymphocytes. Thus, MV replicates preferentially in mature T lymphocytes but will grow well in B cells as well. In vivo infection produces relatively small amounts of recoverable virus. However, when these lymphocytes are cultured in vitro virus replicates very well without added mitogens. These growth patterns may help to understand MV-induced immunologic dysfunction.

Cytotoxic effects of hyperthermia, 5-fluorouracil and their combination on a human leukemia T-lymphoblast cell line, CCRF-CEM

The cytotoxic effects of 5-fluorouracil (FUra), hyperthermia, and the combination of these treatments were examined in a human T-lymphoblast cell line, CCRF-CEM. Simultaneous exposure of exponentially growing CCRF-CEM cells to hyperthermia (39 and 42 degrees C) and FUra (10, 50, and 100 microM) for 1 or 2 hr resulted in subadditive or additive cell kill. When CCRF-CEM cells were exposed to these agents in sequence (hyperthermia----FUra and FUra----hyperthermia) for 1 and 2 hr duration additive cell kill was also observed. Enhanced cytotoxic effects were observed when a longer exposure (4 and 8 hr) to FUra (100 microM) followed heat (42 degrees C for 1 and 2 hr). Heat exposure (42 degrees C, 1 and 2 hr) induced a rapid decrease in the synthesis of DNA of CCRF-CEM cells, followed by a rebound increase at 12 hr and a new decrease at 24 hr. Flow cytometry demonstrated an accumulation of cells in the S phase at 12 hr after heat exposure, followed by a marked increase of the G + M population (maximum at 24 hr). The exposure time, and the sequence of administration of hyperthermia and FUra were critical determinants of cytotoxicity in this in vitro system and might constitute important variables of treatment when these two agents are used clinically.