Autocrine models of B-lymphocyte growth. I. Role of cell contact and soluble factors in T-independent B-cell responses.

The requirements for triggering human B cells to DNA synthesis by T-independent polyclonal activators were examined. Optimal S phase entry of purified resting B cells infected with Epstein-Barr virus (EBV) or confronted with killed particles of Staphylococcus aureus Cowan Strain I (SAC) required a high density of cells in culture. Experiments varying culture vessel geometry and culture volumes revealed that the initial limiting quantity was a soluble activity generated in the B-cell cultures. A parallel observation was noted in the requirements for the sustained growth of EBV-transformed lymphoblasts. Autostimulatory soluble factors harvested from such cultures were able to augment DNA synthesis in low density cultures of resting cells triggered by EBV or SAC. Below a critical cell number, however, soluble factors by themselves, were not sufficient either for supporting primary B-cell responses or for maintaining the proliferation of transformed lymphoblasts. By employing conditions which encouraged cell contact it was found that a second, non-harvestable factor requiring cell proximity for its action was also necessary to promote B-cell growth. The implications of these findings for autocrine and paracrine models of B-cell activation are discussed.     

Effects of low-level microwave irradiation on amphetamine hyperthermia are blockable by naloxone and classically conditionable

In a series of experiments, we investigated the effects of pulsed low-level microwave irradiation on amphetamine-induced hyperthermia in the rat. Rats were irradiated in a 2,450-MHz cylindrical waveguide exposure system at 1 mW/cm², 2 s pulses, 500 pps, average SAR of 0.6 W/kg. Acute (45 min) exposure to microwaves attenuated amphetamine-induced hyperthermia. This effect was blocked by pretreatment of the animals with the narcotic antagonist naloxone. In another experiment, rats were subjected to ten daily sessions of microwave exposure (45 min/session). On day 11, amphetamine-induced hyperthermia was studied in the animals immediately after a session of either microwave or sham exposure. Similar to the acute effect, amphetamine-induced hyperthermia was attenuated in rats irradiated with microwaves (unconditioned effect). In the sham-irradiated animals we observed a potentiation of the amphetamine-induced hyperthermia, which was a conditioned effect of microwaves. Thus, the conditioned effect (potentiation) was opposite in direction to the unconditioned effect (attenuation). No tolerance developed to the unconditioned effect after subchronic exposure. Furthermore, both conditioned and unconditioned effects of microwaves on amphetamine-induced hyperthermia could be blocked by treatment with naloxone. These data suggest that (1) microwave irradiation may activate endogenous opioids, which in turn alter the actions of psychoactive drugs, and (2) the effect of microwaves on drug action can be classically conditioned. Offprint requests to: H. Lai     

Distribution of the [3H]-label from low doses of radioactive ochratoxin a ingested by rats,and evidence for DNA single-strand breaks caused in liver and kidneys

The distribution of a single low dose of [³H]ochratoxin A (OTA) in different tissues of male Wistar rats, after administration by intubation, was investigated after 5 h, 24 h and 48 h. This dose corresponds to concentrations encountered in naturally contaminated feed (4 ppm). The distribution of [³H]-label varied with the time elapsed after administration; at 5 h the highest specific label was found in the stomach contents and in decreasing order in: intestinal contents, lung, liver, kidney, heart, fat, intestine, testes, and the lowest in muscles, spleen and brain. With exception of brain, fat, stomach and lung, all tissues showed maximum levels at 24 h, after which time the label decreased steadily, whereas in fat it increased.After a 12-week feeding experiment, with doses of 288.8 g/kg corresponding to an intake of 4 ppm in feed each 48 h, the DNA in liver and kidneys was investigated for damage. By the alkaline elution method combined with micro-spectrofluorimetric determinations of DNA, evidence for DNA single-strand breaks was obtained. These findings support reports on the carcinogenic action of OTA.     

Autocrine growth of human blymphocytes: Maintained response to autostimulatory factors is the special feature of immortalization by Epstein-Barr virus—A hypothesis

The autocrine growth profile of human B lymphocytes transformed with Epstein-Barr virus (EBV) was found to comprise three distinct components: a B-cell growth factor (BCGF); an interleukin-1 (IL-1)-like activity; an activity requiring cell-to-cell contact for its action. Observations on the inhibition of the EBV-carrying Daudi lymphoma line by α-interferon indicated that loss of response to these autostimulatory factors was underlying growth cessation. Furthermore, a putative for BCGF was found to be down-regulated on B cells stimulated with non-transforming mitogens but constitutively expressed following EBV-transformation. Taken together with recent evidence that normal B cells produce autostimulatory factors, these findings suggest that the special feature of autocrine growth by EBV-immortalized cells is a maintenance of what should normally be a transient phenotype, possibly through deregulation of receptor expression. This hypothesis is discussed.     

Efficient propagation of single gene deleted recombinant Sendai virus vectors

Recombinant Sendai virus vectors (SeVV) have become an attractive tool for basic virological as well as for gene transfer studies. However, to (i) reduce the cellular injury induced by basic recombinant SeV vectors (encoding all six SeV genes as being present in SeV wild-type (wt) genomes) and to (ii) improve SeV vector safety, deletions of viral genes are necessary for the construction of superior SeVV generations. As a strong expression system recombinant replication-incompetent adenoviruses, coding for SeV proteins hemagglutinin-neuraminidase (HN), fusion (F), or matrix (M), were generated and successfully employed for the propagation of single gene deleted (DeltaHN, DeltaF, DeltaM) recombinant SeVV. Further investigations of the propagation procedures required for single gene deleted recombinant SeVV demonstrated (i) modifications of the cell culture medium composition as well as (ii) incubation with vitamin E as crucial steps for the enhancement of SeVV-DeltaHN, -DeltaF, or -DeltaM viral particle yield. Such optimized propagation procedures even led to a successful propagation of HN-deleted viral particles (SeVV-DeltaHN), which has not been reported before.     

Examination of stratum corneum barrier function in vivo by infrared spectroscopy

It is generally accepted that the stratum corneum (SC) is the least permeable layer of the epidermis. Histologically, though, the SC is a non-uniform, inhomogeneous membrane, and the question "Is barrier function distributed uniformly across the SC thickness?" has been posed. To address this issue, human ventral forearm SC has been studied in vivo by attenuated-total-reflectance Fourier-transform infrared spectroscopy during the course of sequential tape-stripping. Because the intercellular lipids of the SC and the degree of hydration of the membrane have been shown to be crucial determinants of barrier function, attention has been focused on the spectral features, which report specifically on these parameters. The degree of disorder of the SC intercellular lipids has been found to decrease over the outer cell layers (up to three tape-strips) and then to remain essentially constant. The amount of lipids decreases similarly such that a 60% reduction (relative to the "no-strip" baseline) is observed after about four tape-strips. A plausible explanation for these measurements is that the lipids near the surface are a mixture of (a) "true" intercellular lipid (which is expected to be highly ordered), and (b) sebaceous lipid (which contains much greater amounts of low-melting components, such as fatty acids). The sequential infrared (IR) spectra provide at least circumstantial evidence to support this hypothesis. As expected, the IR spectra show that SC hydration increases from the surface towards the SC-stratum granulosum interface. Taken together, the results imply that the SC is indeed non-uniform. The properties of the outer layers (those removed by the first 3-4 tape-strips) change significantly with increasing depth.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early phase II Gynecologic Oncology Group experience with ifosfamide/mesna in gynecologic malignancies

Starting in July 1985, the Gynecologic Oncology Group conducted a series of phase II trials with ifosfamide/mesna in advanced or recurrent gynecologic malignancies. Previously untreated patients received 1.5 g/m² i.v. ifosfamide daily for 5 days. Mesna was given i.v. q4h×3 following ifosfamide; each dose was 20% of the daily ifosfamide dose. All patients with ovarian and 87% of those with cervical cancer had previously undergone platinum-based therapy. Because of the toxicity encountered in previously treated patients with ovarian carcinoma, the dose of ifosfamide was reduced to 1.2 g/m² daily in all patients who had received prior chemo- or radiotherapy. In epithelial ovarian carcinoma, responses were observed in 8 (20.0%) of 41 evaluable patiens, with 3 (7.0%) complete responses. Response duration was 2.1–20.3+ months, with a median of 6.9+ months. In squamous-cell carcinoma of the cervix, 3 (11.1%) of 27 evaluable patients showed partial responses of 1.8, 2.2, and 3.1 months' duration. Of 26 untreated patients with mixed mesodermal tumors of the uterus, 5 (19.2%) achieved complete and 3 (11.5%) showed partial responses, for an overall response rate of 30.7%. Response duration was 1.4+-8.6 months, with a median of 3.8 months. Toxicity included two deaths due to renal insufficiency and a third related to neurologic impairment. Hematologic toxicity was manageable. Ifosfamide/mesna has activity in a wide range of gynecologic malignancies.Presented at the Satellite Symposium Ifosfamide in Gynecological Tumors of the 5th European Conference on Clinical Oncology and Cancer Nursing, London, September 3–7, 1989     

Indocyanine green angiography of choroidal tumors

Background: Fluorescein angiography (FA) has been widely used in the diagnostic evaluation of cboroidal tumors. Indocyanine green angiography (ICG-A), which permits better visualization of choroidal vasculature than FA, has been recently introduced into clinical practice. Only few reports exist on the ICG-A characteristics of choroidal tumors. Methods: The fluorescein and indocyanine green angiograms of 61 patients were assessed. These included 14 patients with choroidal nevi, 30 with malignant melanomas, 7 with suspected melanomas or atypical nevi, 5 with hemangiomas and 5 with metastases. Results: The outline of pigmented tumors was more accurate on ICG-A than on FA. Characteristic patterns were seen in all intra-ocular tumors with ICG-A, so it was possible to distinguish hemangiomas from malignant lesions. Characteristic features of malignant melanomas include abnormal vascular pattern and marginal late dye leakage. None of the benign lesions showed these features. In suspected melanomas, the presence of abnormal choroidal vascular patterns and/or late dye leakage on ICG-A may indicate malignancy. Conclusion: The study suggests that ICG-A can yield additional information that is useful in differentiating amongst choroidal tumors. Better delineation of pigmented lesions with ICG-A allows more accurate treatment planning and follow-up.     

The impact of clozapine treatment on serum lipids in chronic schizophrenic patients

The aim of this retrospective study is to determine whether lipid levels rise in neuroleptic-resistant chronic schizophrenic patients during clozapine treatment and if this rise is correlated with a decrease in aggressive and suicidal behavior. Seventy neuroleptic-resistant schizophrenic patients treated with clozapine for at least 6 months were compared with 30 chronic schizophrenic patients treated with classic antipsychotic agents for the same length of time. Data on serum levels of cholesterol and triglycerides and on aggressive and suicidal behavior, as measured by the Overt Aggression Scale (OAS), were collected in both groups before treatment and 6 months later. A significant reduction in aggressive and suicidal behavior was noted in the clozapine-treated group but not in the classical antipsychotic-treated group. Clozapine treatment was associated with an elevation in serum triglyceride level, whereas classic antipsychotic treatment was associated with an increase in serum cholesterol level. We conclude that serum cholesterol level does not play a role in the clozapine-induced attenuation in aggressive and suicidal behavior in neuroleptic-resistant schizophrenic patients, though the accompanying elevation in triglycerides may be relevant to a behavioral effect.