[CT-guided fine needle aspiration biopsy of abdominal masses]

Fine needle aspiration biopsy were made under CT guidance of 50 cases of intra-abdominal masses, including liver in 37 cases, kidney in 6, pancreas and spleen in 1 respectively, and 5 biopsies were made of tumors of the abdominal cavity. The overall diagnostic accuracy was 92%, and the accuracy for malignancies was 84.6%. No complications occurred related to the procedure. The relevant factors for precise biopsy safety and the therapeutic value of this technique were discussed. It was concluded that CT-guided fine needle aspiration biopsy is precise in localization, it is a safe approach yielding satisfactory diagnostic accuracy.

[Effects of guan-fu base A on fast response action potentials of papillary muscles of guinea pigs]

Guan-fu base A is a new alkaloid first isolated from the tuber of Aconitum coreanum in China. The electrophysiological effects of guan-fu base A were examined on the isolated papillary muscles of guinea pigs by glass-microelectrode technique coupled with microcomputer real-time analysis. Guan-fu base A 50 micrograms/ml had less effect on RP, but markedly decreased Vmax and APA of the fast response action potentials. The action potential duration was shortened at all voltage levels and plateau height was lowered. ERP was prolonged relatively and activation voltage became more negative. The inhibition of guan-fu base A on Vmax showed frequency dependent effects. The above results suggested that guan-fu base A could block the fast Na+ channels and exhibited anti-arrhythmic action.

Acute and chronic effects of corticotropin-releasing factor on schedule-controlled responding and neurochemistry of pigeons

Key pecking by pigeons was maintained under various schedules of food presentation. Acute i.c.v. administration of corticotropin-releasing factor (CRF) (3.0-30.0 micrograms/kg) decreased responding in both components of a multiple 3-min fixed-interval, 30-response fixed-ratio schedule and under a multiple fixed-ratio schedule in which responding during one component was punished by shock delivery. The rate-decreasing effects of intermediate doses of CRF were blocked by the CRF antagonist alpha-helical CRF9-41 under the multiple fixed-internal fixed-ratio schedule, with 10.0 micrograms/kg of the antagonist producing a more complete reversal than 30.0 micrograms/kg. The rate-reducing effects of 10.0 and 30.0 micrograms/kg of CRF disappeared rapidly when CRF was administered daily, with complete restoration of responding occurring by the 4th day of chronic administration. Acute effects were recovered when CRF administration was discontinued for 7 to 14 days. Analyses of cerebrospinal fluid revealed that behaviorally active doses of CRF produced large, dose-dependent increases in levels of the serotonin metabolite 5-hydroxyindoleacetic acid and in the dopamine metabolites dihydroxyphenylacetic acid and homovanillic acid; smaller increases also occurred in the levels of 3-methoxy-4-hydroxyphenylethylene glycol, the metabolite of norepinephrine. Chronic administration of 30 micrograms/kg of CRF for a 4-day period did not reveal any change in metabolite levels when compared to those obtained after acute administration, with the exception of 3-methoxy-4-hydroxyphenylethylene glycol which approached control levels after chronic CRF. These results indicate that, as is the case with mammals, CRF has potent behavioral and neurochemical activity in avian species and that tolerance occurs rapidly to the behavioral effects.

[Cellular DNA content of human cervical carcinoma]

Microspectrophotometric measurement of the cellular DNA content of 73 cervical carcinoma specimens was carried out. The tumor was diploid in 7 cases, tetraploid in 2 and aneuploid in 64. The cases could be divided into hyperploid and hypoploid groups using the DNA index of 1.5 as demarcation. The DNA content was found to be closely related to the histologic types and mitotic figures of the tumors. Hyperploidy was more frequently seen in large-cell carcinoma and hypoploidy in small-cell varieties.

Generation of an antibody with a designed specificity difference for protein C and activated protein C

Rabbit polyclonal antibodies to a synthetic peptide, NH2-Asp-Thr-Asn-Gln-Val-Asp-Gln-Lys-Asp-Gln-Leu-Asp-Phe-Arg-CONH2 (A Pep), have been produced. This sequence is identical to that contained in the tetradecapeptide released from bovine protein C (PC) as a result of its conversion to its activated form (APC), except that Phe13 replaced the normal Pro13, in order to discourage cross-reactivity of antibodies to the carboxylterminal portion of APep with PC. The antibody pool obtained reacted with PC and showed virtually no cross-reactivity toward either APC or several typical plasma proteins. This general approach should serve well as a means of production of antibodies with a designed specificity capable of distinguishing between forms of the same protein that arise by release of peptide material.

Adhesive and degradative properties of human placental cytotrophoblast cells in vitro

Human fetal development depends on the embryo rapidly gaining access to the maternal circulation. The trophoblast cells that form the fetal portion of the human placenta have solved this problem by transiently exhibiting certain tumor-like properties. Thus, during early pregnancy fetal cytotrophoblast cells invade the uterus and its arterial network. This process peaks during the twelfth week of pregnancy and declines rapidly thereafter, suggesting that the highly specialized, invasive behavior of the cytotrophoblast cells is closely regulated. Since little is known about the actual mechanisms involved, we developed an isolation procedure for cytotrophoblasts from placentas of different gestational ages to study their adhesive and invasive properties in vitro. Cytotrophoblasts isolated from first, second, and third trimester human placentas were plated on the basement membrane-like extracellular matrix produced by the PF HR9 teratocarcinoma cell line. Cells from all trimesters expressed the calcium-dependent cell adhesion molecule cell-CAM 120/80 (E-cadherin) which, in the placenta, is specific for cytotrophoblasts. However, only the first trimester cytotrophoblast cells degraded the matrices on which they were cultured, leaving large gaps in the basement membrane substrates and releasing low molecular mass 3H-labeled matrix components into the medium. No similar degradative activity was observed when second or third trimester cytotrophoblast cells, first trimester human placental fibroblasts, or the human choriocarcinoma cell lines BeWo and JAR were cultured on radiolabeled matrices. To begin to understand the biochemical basis of this degradative behavior, the substrate gel technique was used to analyze the cell-associated and secreted proteinase activities expressed by early, mid, and late gestation cytotrophoblasts. Several gelatin-degrading proteinases were uniquely expressed by early gestation, invasive cytotrophoblasts, and all these activities could be abolished by inhibitors of metalloproteinases. By early second trimester, the time when cytotrophoblast invasion rapidly diminishes in vivo, the proteinase pattern of the cytotrophoblasts was identical to that of term, noninvasive cells. These results are the first evidence suggesting that specialized, temporally regulated metalloproteinases are involved in trophoblast invasion of the uterus. Since the cytotrophoblasts from first trimester and later gestation placentas maintain for several days the temporally regulated degradative behavior displayed in vivo, the short-term cytotrophoblast outgrowth culture system described here should be useful in studying some of the early events in human placen

Micrococcal nuclease as a probe for bound and distorted DNA in lac transcription and repression complexes

Micrococcal nuclease (MNase) is used to probe the structure of transcription and repression complexes at the lac regulatory region in vitro. Both the lac operator, 01, and the pseudo-operator, 03, are found to be protected from MNase digestion by the lac repressor on supercoiled DNA, and hypersensitive sites appear on both strands around nucleotide (nt) -26 between 01 and 03. This hyperreactive site is coincident with the site of the DNA kink shown previously to form within a loop caused by simultaneous repressor binding to 01 and 03. MNase hypersites are also observed both upstream from cAMP receptor protein (CRP) and downstream from bound RNA polymerase in open promoter complexes. In both open and closed complexes the binding of polymerase partially protects the backbone from MNase attack. Catabolite activator protein is shown to be required for both closed and open complex formation. Taken together with previous footprinting data, the results suggest that lac transcription complexes involve DNA bent towards a protein core consisting of RNA polymerase and catabolite activator protein.

Analysis of cytotoxic T cell precursor frequencies directed against individual HLA-A and -B alloantigens

We describe here a limiting dilution analysis to determine cytotoxic T lymphocyte precursor (CTLp) frequencies against individual HLA-A or -B antigens. This assay is reproducible and showed that the CTLp frequency of an individual remains stable with time. Significant variations in CTLp frequency against the same alloantigen were found in different individuals and even in monozygotic twins, showing that these differences were not (completely) genetically determined. Within an individual, a wide range of CTLp frequencies can be found against different allo-antigens. Serologically cross-reactivity seems not to interfere in this assay. This LDA is a practicable tool for a systematic analysis of CTLp response against selected individual HLA-A or -B antigens and can be used for the selection of HLA mismatched donors for transplantation patients.

Pathogenetic role of anti-vascular endothelial cell antibodies in systemic lupus erythematosus

In order to study the relationship between vascular endothelial cell (VEC) antigen system and systemic lupus erythematosus (SLE), including lupus nephritis, Terasaki's microcytotoxicity test and indirect immunofluorescence were used to detect anti-VEC antibody. VEC was identified by electron microscopy. Sera of 21 SLE patients and of 100 healthy donors were examined. Among the 21 SLE patients evaluated, 17 had kidney injury and 13 were in active stage SLE. Results showed that anti-VEC antibody was found in 76.2% of 21 SLE patients, while only 1% of the controls were positive (P less than 0.05). This antibody was detected in 84.6% of patients in active stage SLE and in 62.5% of patients in inactive stage (P greater than 0.05). In patients with and without kidney injury, it was detected in 82.4% and 50%, respectively (P greater than 0.05). These data show that anti-VEC antibody does exist in the sera of SLE patients, the presence of which is closely related to SLE onset and is independent of whether the patient is in active stage of SLE or has kidney injury. In summary, our data suggest that anti-VEC antibody may be one of the triggering factors in the vasculitis of SLE. It is proposed that renal VEC may act as a target cell which can be attacked by anti-VEC antibody to constitute an in-situ immune complex formation in the kidney, leading to lupus nephritis.

Benzodiazepine analogues L365,260 and L364,718 as gastrin and pancreatic CCK receptor antagonists

We examined the ability of the recently described 3-(benzoylamino)benzodiazepine analogue L365,260 and the 3-(acylamino)benzodiazepine analogue L364,718 to distinguish gastrin from pancreatic cholecystokinin (CCK) receptors. Neither L365,260 nor L364,718 when present alone (1 microM) caused stimulation of amylase release from guinea pig pancreatic acini or caused contraction of smooth muscle cells from guinea pig stomach. Each analogue inhibited CCK-stimulated amylase release, gastrin-17-I-stimulated smooth muscle contraction, binding of 125I-Bolton-Hunter-cholecystokinin octapeptide (125I-BH-CCK-8) to pancreatic CCK receptors, and binding of 125I-gastrin-17-I to gastrin receptors on pancreatic acini. L365,260, (Ki, 7.3 +/- 0.8 nM) was 50-70 times more potent than L364,718 at inhibiting binding of 125I-gastrin to pancreatic acini or gastrin-stimulated smooth muscle contraction. In contrast, L364,718 (Ki, 4 +/- 1 nM) was 145-200 times more potent than L365,260 at inhibiting binding of 125I-BH-CCK-8 to pancreatic acini or CCK-stimulated amylase release. Neither L364,718 nor L365,260 distinguished between high- and low-affinity CCK binding sites. L365,260 and L364,718 did not inhibit binding of radiolabeled vasoactive intestinal peptide, secretin, bombesin, substance P, or N-methylscopolamine to pancreatic acini. These results demonstrate that, in contrast to other gastrin-CCK receptor antagonists described, L365,260 is a selective gastrin receptor antagonist having an 80-fold higher affinity for gastrin than pancreatic CCK receptor, whereas L364,718 has a 125-fold higher affinity for pancreatic CCK receptors. Because of the selectivity of these two antagonists the involvement of CCK and gastrin in various physiological processes can be differentiated even when both receptors occur on the same cell.

Gamma-glutamyl transpeptidase activity in superficial exfoliated cells during hamster buccal pouch carcinogenesis

The study of gamma-glutamyl transpeptidase (GGT) activity in transformed tissues has conventionally involved the killing of an animal or excision of the lesion, preventing longitudinal study. Oral exfoliative cytology allows longitudinal examination; however, it has been shown to be an unreliable criterion of malignancy. GGT activity has been demonstrated histochemically to involve the full thickness of the epithelium, including the keratin layer during carcinogenesis of hamster buccal pouch epithelium. This study correlates the GGT-stained foci in tissue sections and the proportion of GGT-positive cells in a superficial smear during a 13-week regime of tri-weekly topical application of 7,12-dimethylbenz[a]-anthracene (DMBA) in mineral oil. GGT-positive cells were detected in smears 3 weeks after application of the carcinogen, coincident with GGT-positive foci in tissue sections involving the keratin layer. The proportion of GGT-positive cells in each experimental period increased during the first 7 weeks of the experiment and plateaued thereafter. The number of GGT-positive foci in tissue sections in each experimental period also increased during the experiment. GGT activity was not detected in either smears or tissue sections of untreated or mineral oil treated mucosa. The correlation between the proportion of GGT-positive cells in smears and GGT-positive foci in tissue sections suggest the possibility of studying the GGT activity in an experimentally induced lesion without its elimination. Furthermore, oral exfoliative cytology using GGT staining may be useful in detecting precancerous lesions clinically.

[Retinal function test of eyes with opaque refractive media]

The characteristics of the laser interference fringes of opaque lenses were studied by the laser speckle method. After studies with the opaque lenses in the laboratory, the method was employed in the clinic. The preoperative laser interference fringe visual acuities were compared with the postoperative corrected visual acuities in 65 eyes with mature cataract and 8 eyes with cornea opacities. The authors concluded that the laser speckle interferometry estimated the retinal function of eyes with opaque refractive media quantitatively and it demonstrated practical value in the clinic.

The effect of edible black tree fungus (Auricuaria auricula) on experimental atherosclerosis in rabbits

The effects of edible black tree fungus (BFF) compared with aspirin on serum lipid level and experimental atherosclerosis and thrombosis in rabbits were studied. The results showed that total serum cholesterol and B-lipoprotein of the BTF group were significantly decreased (P less than 0.01) than the aspirin group and the group with neither BTF nor aspirin. There were less aortic atherosclerotic plaque and intramyocardial arterial lumen stenosis in the BTF group. The development of thrombus and platelet aggregation and thromboxane TXB2 level were inhibited both in the BTF and aspirin group (P less than 0.01). These findings indicate BTF may be used as a healthy food in preventing atherosclerosis and coronary heart disease, but its mechanism requires further investigation.

Investigation on genetic traits and selection of interspecific somatic hybrid progenies in tobacco

The interspecific somatic hybrid plants were produced in 1980 by protoplast fusions between N. tabacum and N. rustica, and N. tabacum and N. glauca. The results of this study on the genetic traits and selection of the hybrid progenies for seven years showed that the performances of the somatic hybrids (SH) were typical intermediate forms of the two species involved in each somatic hybridization, and that segregation began in SH3 and (SH)BC2 generations (the SH1 backcrossed to N. tabacum twice). However, stable lines and male sterile lines from SH1 until the present, were also obtained. The fertilities of the hybrid progenies were generally poor. The characteristics of the recurrent parent were accumulated, and the chromosome numbers of the hybrid plants were gradually decreased as the number of backcrossing generations increased. Some new types of tobacco with certain commercial values have been selected for used in the present study. The conclusion reached, based on our results, is that the somatic hybridization technology has now been successfully utilized to create unique breeding lines of tobacco, and represents a powerful, new tool for crop improvement.

Central neurotensin affects rat gastric integrity, prostaglandin E2, and blood flow

The aim of this study is to define the effect(s) of centrally administered neurotensin (NT) on gastric mucosal integrity, prostaglandin E2 (PGE2) generation, and blood flow during stress induced by cold-water restraint (CWR) in rats. Intracerebroventricular (icv) NT reduced macroscopic and microscopic damage. The former effect was dose dependent and was totally blocked by indomethacin pretreatment. Gastric mucosal PGE2 increased 27 and 30% at 30 and 60 min, respectively, in nonrestrained rats given icv NT. PGE2 generation was reduced in control rats during CWR but was maintained in CWR rats treated with icv NT. Gastric mucosal blood flow (GMBF) was significantly reduced in control rats during CWR. Mucosal blood flow was maintained at nonrestraint levels in the presence of icv NT during CWR; however, this effect was abolished by parenteral indomethacin pretreatment. Similarly, intravenous 16,16-dimethyl-PGE2 (200 micrograms.kg-1.h-1) maintained GMBF of non-CWR levels as well as preventing the macroscopic damage normally associated with CWR. These data suggest a protective role for central NT on the gastric mucosa, mediated, at least in part, by PGE2 generation and gastric mucosal blood flow.

Effect of Mycobacterium tuberculosis-derived sulfolipid I on human phagocytic cells

Experiments were performed to determine the effects of Mycobacterium tuberculosis-derived sulfolipid I on phagocytic cells. Sulfolipid I was taken up in significant amounts by human neutrophils and in lesser amounts by monocytes and lymphocytes. Superoxide (O2-) production by neutrophils was significantly increased by sulfolipid I, but the rate of production was slower than that reported previously for other stimuli. The optimal concentration of sulfolipid I for stimulation of O2- production was 27 micrograms/ml, while higher concentrations produced less. At substimulatory levels sulfolipid I caused enhancement of O2- release from neutrophils when it was subsequently stimulated by other agents. Nonadherent monocytes from most normal donors failed to produce O2- when treated with sulfolipid I; however, adherent monocytes pretreated with gamma interferon did produce O2- with sulfolipid I stimulation. Priming for an enhanced oxidative response of activated monocytes was also observed. These sulfolipid I-induced changes in phagocytic cell function may be important in altering the ability of phagocytes to respond effectively to M. tuberculosis and may also cause exaggerated inflammatory responses.

An analogue of substance P with broad receptor antagonist activity

[DPro4,DTrp7,9,10]Substance P-4-11 functions as a substance P receptor antagonist in several different systems. Because some analogues of substance P can function as receptor antagonists for bombesin as well as substance P, we tested [DPro4,DTrp7,9,10]substance P-4-11 for its ability to modify the interaction of various pancreatic secretagogues with their receptors in dispersed acini from guinea pig pancreas. [DPro4,DTrp7,9,19]Substance P-4-11 did not stimulate amylase secretion and did not alter the stimulation of amylase secretion caused by secretin, vasoactive intestinal peptide, calcitonin gene-related peptide or carbachol, but did inhibit the stimulation of amylase secretion caused by substance P, bombesin or cholecystokinin. With substance P, bombesin and cholecystokinin, [DPro4,DTrp7,9,10]substance P-4-11 caused a parallel rightward shift in the dose-response curve for stimulation of amylase secretion with no change in the maximal response. Schild plots of these results gave straight lines with slopes that were not significantly different from unity. [DPro4,DTrp7,9,10]Substance P-4-11 inhibited binding of 125I-labeled substance P, 125I-[Tyr4]bombesin and 125I-cholecystokinin octapeptide over the same range of concentrations as that in which it inhibited biologic activity of each of these peptides. Half-maximal inhibition of binding of 125I-substance P occurred with 4 microM, of 125I-[Tyr4]bombesin with 17 microM and of 125I-cholecystokinin octapeptide with 5 microM. With each radiolabeled peptide the value of Ki for inhibition of binding by [DPro4,DTrp7,9,10]substance P-4-11 was not significantly different from the corresponding value of Ki calculated from the appropriate Schild plot. The present results indicate that [DPro4,DTrp7,9,10]substance P-4-11 is a competitive antagonist at receptors for substance P, for bombesin and for cholecystokinin. Thus, these receptors must share a common peptide recognition mechanism even though they interact with agonists that have no obvious structural similarity.

Intracellular injection of Ca2+ chelator does not affect spike repolarization of cat spinal motoneurons

Both intra- and extracellular injections of tetraethylammonium (TEA) prolonged the spike repolarization of motoneurons in the spinal cord of cats under pentabarbitone anaesthesia, but did not depress the afterhyperpolarization (AHP). Intracellular injections of EGTA and the fast-acting Ca2+ chelator, BAPTA, greatly depressed the AHP, but the spike shape remained unchanged. Extracellular applications of Cd2+ had similar effects. These observations suggest that a Ca2+-dependent K+ outward current is not a major mechanism of spike repolarization in motoneurons.

Effects of cyclophosphamide and a metabolite, acrolein, on Naegleria fowleri in vitro and in vivo

Mice challenged intranasally with Naegleria fowleri died of primary amoebic meningoencephalitis. Mice given 30 mg of cyclophosphamide per kg of body weight daily for 10 days starting 2 days before challenge were protected. Neither cyclophosphamide nor serum from cyclophosphamide-treated mice inhibited N. fowleri in vitro. A metabolic product of cyclophosphamide, acrolein, inhibited growth and enflagellation of N. fowleri. Acrolein at 40 microM was amoebicidal. Acrolein injured starved cells and amoebae at 5 degrees C and growing N. fowleri.

Interference filters as nonlinear decision-making elements for three-spot pattern recognition and associative memories

Simple patterns consisting of three spots (V and Gamma) have been recognized by dividing, shifting, and recombining beams onto bistable ZnS interference filters. This experiment demonstrates AND-gate operation, cascading, and a moderate amount of parallelism, but a laser power of several watts was required and the response times were several milliseconds. An associative memory for fingerprint identification has been constructed using a VanderLugt correlator and an interference filter as a reflective thresholding device.

[Luteinizing hormone-releasing hormone (LRH) agonist in the treatment of breast cancer, osteosarcoma and prostate carcinoma--analysis of 12 patients]

This paper first reports the results of 12 patients with sex hormone-dependent neoplasms, including 9 women with breast cancer, 2 men with osteosarcoma and 1 man with prostate carcinoma, treated by LRH agonist, (D-Ala6, des-Gly-NH2(10))-LRH-ethylamide (LRH-A) 100-200 micrograms, IM, QD. After 15-30 days of administration, the concentrations of plasma mean estradiol, progesterone, testosterone, serum luteinizing hormone and follicle-stimulating hormone were lowered significantly in the peripheral blood of all patients, associating with improvement of the patients' general condition and reduction of the tumors and/or metastatic foci. No serious side effects were observed except vaginal irregular bleeding in isolated patients. Three patients died and the others were alive in follow-up of 4-30 months. The results suggest that LRH-A be useful in the treatment of the sex hormone-dependent tumors and worth further study.

Proliferative activity of murine mammary epithelium as affected by dietary fat and calcium

Dietary fat and calcium have been found to affect significantly the proliferative status of the mammary glands. Female mice (3-week-old C57BL/6J) were given either a low or high corn oil diet (3 or 30% by weight). One, 2, or 4 weeks after the dietary intervention the animals were given injections of [3H]thymidine and/or colchicine; 2 h later their thoracic mammary glands were removed and processed for histology and autoradiography. Animals on the high corn oil diet had an increased labeling index of both terminal ducts and mature ducts compared to the control group at each time (i.e., 10.1 +/- 2.1 versus 4.8 +/- 0.9% at 2 weeks). This effect of a high corn oil diet was evident on the mammary glands of animals at various ages. Animals on a high beef tallow diet also had a high labeling index. This effect of a high fat diet appeared to be reduced by dietary calcium. The labeling index for terminal ducts of animals on high corn oil diet decreased from 14.1 +/- 3.8, 11.9 +/- 3.4 to 8.5 +/- 1.8 and high beef tallow from 13.6 +/- 3.6, 11.4 +/- 0.7 to 9.5 +/- 1.3 for calcium levels of 0.1, 0.5, and 1.0%, respectively. Mitotic indices followed the same trend. These studies demonstrate that a high fat diet affects the proliferative status in the mouse mammary glands in a short period of time and that this effect can be reduced by dietary calcium.

DNA supercoiling promotes formation of a bent repression loop in lac DNA

Titration experiments on supercoiled lac DNA show that one repressor tetramer can bind simultaneously to the primary lac operator and to the very weak lac pseudo-operator, located 93 base-pairs apart. The formation of this complex is accompanied by the appearance of an extreme hypersensitive site in a five base-pair sequence located approximately midway between the operators. This remote sequence is hypersensitive to attack by two different chemical probes, dimethyl sulfate and potassium permanganate, the latter of which is a new probe for distorted DNA. We interpret these results in terms of a complex in which lac repressor holds two remote operators together in a DNA loop. The formation of this bent DNA loop requires negative DNA supercoiling. In vivo, both lac operators bind repressor even though the presence of multiple operator copies has forced the two operators to compete for a limited amount of repressor. This suggests that the operator and pseudo-operator have similar affinities for repressor in vivo. Such similar affinities were observed in vitro only when DNA supercoiling forced formation of a repression loop.

Gamma-glutamyl transpeptidase activity during carcinogenesis of hamster buccal pouch epithelium

Gamma-glutamyl transpeptidase (GGT) activity has been demonstrated histochemically in a number of experimentally induced neoplasms and has been suggested as a label for potential precursors for the development of squamous cell carcinomas. This study explores the kinetics of GGT-stained cell populations, their correlation with the hypothesized initiated cells and evidence of malignant transformation of epithelium in hamster buccal pouch by a 15-week regime of tri-weekly topical application of 7, 12-dimethylbenz[a]anthracene (DMBA) in mineral oil. GGT-positive foci were detected histochemically in tissue sections as early as 1 week after application of the carcinogen, when there was no morphological evidence of dysplasia. The average number of the GGT-positive foci in each experimental period was found to increase with time. Even though the majority of the foci were small, consisting of only a single cell or a small group of cells, a few larger GGT-positive lesions were noted, particularly in the later period of the experiment. A total of 66 grossly visible neoplasms were found. Thirty-seven of these were submitted for GGT staining. Thirty-two (86.5%) of these showed patchy GGT activity, primarily in the superficial epithelial cells and/or the keratin. In the non-neoplastic epithelium, the GGT staining could involve any or all layers of cells. GGT activity was not detected in untreated or mineral oil-treated mucosa. The results of this study support the hypothesis that GGT activity may label potential precursors for the development of squamous cell carcinomas.

Effects of intracellular injections of phorbol ester and protein kinase C on cat spinal motoneurons in vivo

In cat spinal motoneurons intracellular iontophoresis of phorbol 12, 13-diacetate or protein kinase C increases the afterhyperpolarization, the maximum rate of spike rise and the spike peak amplitude, without evident change in resting potential, input resistance and monosynaptic excitatory postsynaptic potential. Phorbol ester also reduces the accommodation of repetitive discharge evoked by intracellular current pulses. These data suggest that activation of protein kinase C facilitates the Ca2+-activated K+ current that mediates the afterhyperpolarization, as well as the fast Na+ current. These effects are quite different from those seen in some other mammalian central neurons.

In vitro alterations of tracheal epithelium of hamsters by carcinogens in organ culture

In vitro organ culture of the hamster's trachea was improved and applied to a carcinogenesis research. The rotary culture enabled explants of tracheal epithelium to survive more than 8 weeks. The study was composed of 2 kinds of culture; untreated and treated with carcinogens. In the untreated culture, Eagle MEM medium had the same culture effect as RPMI 1640 medium. With prolongation of culture time (particularly longer than 5 weeks), irreversible degenerative changes appeared in epithelial cells. Culture for 4 weeks was usually thought to be appropriate for experimental research. In the treated culture, the effect of benzo-(a) pyrene (B(a)P) and B(a)P + cigarette smoking condensate-neutral fraction (CSC-NF) on tracheal epithelium was investigated with light and electron microscopies (TEM and SEM) and autoradiography. Atypical hyperplasia with or without lesions suggesting carcinoma in situ was induced by B(a)P + CSC-NF more evidently and frequently than by B(a)P alone. The present findings corroborated the cocarcinogenetic effect of CSC-NF.

Apamin depresses selectively the after-hyperpolarization of cat spinal motoneurons

Extra- (but not intra-) -cellularly applied apamin depresses selectively the after-hyperpolarization (AHP) of cat spinal motoneurons in situ, while causing only a slight depolarization and minor changes in size and shape of the action potential. Apamin increases firing evoked by long depolarizing current pulses. These results indicate that the Ca2+-dependent K conductance underlying the AHP is sensitive to apamin, and that this conductance is likely to have a physiological role in the control of motoneuronal firing.

Mechanism of Action of Pseudomonas syringae Phytotoxin, Syringomycin : Stimulation of Red Beet Plasma Membrane ATPase Activity

Syringomycin, a peptide toxin produced by the phytopathogen Pseudomonas syringae pv syringae preferentially stimulated (2-fold) the vanadate-sensitive ATPase activity associated with the plasma membrane of red beet storage tissue. The toxin had a very slight effect on the tonoplast ATPase and had no detectable effect on the mitochondrial ATPase. Optimal stimulation was achieved with 10 to 50 micrograms of syringomycin per 25 micrograms of membrane protein. Treatment of membranes with 0.1% (weight/volume) deoxycholate eliminated the activation effect, and enzyme solubilized with Zwittergent 3-14 was not affected by syringomycin. ATPase activity was activated to the same extent at KCl concentrations ranging from 0 to 50 millimolar. Valinomycin, nigericin, carbonylcyanide p-trifluoromethoxyphenylhydrazone, and gramicidin did not increase the plasma membrane ATPase activity. However, these ionophores did not hinder the ability of syringomycin to stimulate the activity. We suggest that syringomycin does not increase ATPase activity by altering membrane ion gradients nor directly interacting with the enzyme, but possibly through regulatory effectors or covalent modification of the enzyme.

Effects of 4-aminopyridine on the action potential and the after-hyperpolarization of cat spinal motoneurons

In cats under pentobarbital anaesthesia, intramotoneuronal administrations of 4-aminopyridine significantly prolong the falling phase of the antidromic action potential but have much less effect on the orthodromic action potential. 4-aminopyridine probably blocks the fast K channels involved in the repolarization of the membrane and indirectly activates ionic channels through enhancement of synaptic transmission, also suggested by the potentiation of excitatory postsynaptic potentials. In many cells, 4-aminopyridine depresses the amplitude and prolongs the time course of the after-hyperpolarization; therefore 4-aminopyridine may also partly block Ca2+-activated K+ channels.

Mechanism of action of Pseudomonas syringae phytotoxin, syringomycin. Interaction with the plasma membrane of wild-type and respiratory-deficient strains of Saccharomyces cerevisiae

The effects of the phytotoxin, syringomycin, produced by Pseudomonas syringae pv. syringae, were examined on cells of a wild-type and a respiratory-deficient (rho0) mutant of Saccharomyces cerevisiae. The growth of both strains in liquid culture was inhibited by 0.5 micrograms syringomycin per ml and higher. Uptake rates of tetraphenylphosphonium and dimethyloxazolidine ions in cell suspensions of both strains increased when 1.5 micrograms per ml syringomycin was added. These responses were kinetically and quantitatively similar in the two strains and indicated increases in electrical potential (cell interior negative) and pH differences (cell interior alkaline) across the plasma membrane. Glucose (0.1 M) enhanced the effect on the electrical potential, was required for the pH changes, and increased the cellular ATP levels. These results show that the effects of syringomycin are energy-dependent and are due to alterations of plasma membrane and not to mitochondrial function.

Why TCP timers don't work well

Repeated observation of TCP retransmission timer problems stimulated investigation into the roles and limitations of timers. Timers are indispensable tools in building up reliable distributed systems. However, as the experience with the TCP retransmission timer has shown, timers have intrinsic limitations in offering optimal performance. Any timeout based action is a guess based on incomplete information, and as such is bound to be non-optimal. We conclude that, if we aim at high performance, we should use external events as a first line of defense against failures, and depend on timers only in cases where external notification has failed.

[Prognostic analysis of four pathological features in carcinoma of the uterine cervix and its clinical significance]

The correlation between different pathological features of biopsy specimen and the five year survival rate of 442 patients with carcinoma of uterine cervix treated in our hospital during 1968 to 1980, were studied by means of gradual regression. The result showed that the five year survival rate was influenced, at different levels, by the pathological features. The peritumoral lymphocytic infiltration was the most significant factor influencing the prognosis. Then were the fibrous tissue reaction and the cell type but the mode of invasion was insignificant. The best regression equation to predict the prognosis of patients with carcinoma of uterine cervix was established by gradual choosing. By this equation, we could directly calculate the probability of the five year survival of the patient. It was proved by retrospective and prospective analysis that the equation could accurately reflect the real five year survival rate of patients with carcinoma of uterine cervix.