Dynamics of secretion.

In this short review, kinetic aspects of exocytosis are discussed. A special emphasis is put on recent data that highlight dynamic differences between neurotransmission and other forms of secretion.

Kinetics of neuronal and endocrine secretion.

Calcium (Ca2+) regulated secretion/exocytosis is a key mechanism for cell-cell communication. Neurotransmission and hormone release are the most studied and the best characterized of all secretion systems so far. Here, some dynamic aspects of secretory vesicle trafficking will be briefly reviewed with special emphasis on the differences between synaptic vesicle and dense-core vesicle turnover.

Expression of protein kinase C beta1 confers resistance to TNFalpha- and paclitaxel-induced apoptosis in HT-29 colon carcinoma cells.

The expression of different protein kinase C (PKC) isoenzymes has been shown to vary with proliferation rates, differentiation or apoptosis in normal colon crypts. In addition, the activity of some PKC isoenzymes appears to be reduced in colorectal cancer. The aim of the present work was to determine whether modulation of PKC expression would affect the susceptibility of a p53-defective colon carcinoma cell line to different apoptotic treatments. HT-29 cells exhibited sensitivity to paclitaxel (Taxol) and tumor necrosis factor alpha (TNFalpha) in a dose- and time-dependent manner but were relatively resistant to etoposide. Inhibition of PKC activity augmented the susceptibility of HT-29 cells to apoptosis, and phorbol ester induction of PKC reduced such susceptibility. Transfected HT-29(PKC) cells, hyper-expressing the beta1 isoform of PKC, were less sensitive to TNFalpha and paclitaxel than the normal counterpart. The present data 1) indicate that the expression of PKC influences the susceptibility of HT-29 colon cancer cells to apoptotic drugs apparently regardless of their mechanism of action, and 2) suggest paclitaxel as a potential candidate for the treatment of colon cancer, possibly in association with inhibitors of PKC (alpha and beta) at doses not cytotoxic per se.

Transformation by oncogenic ras-p21 alters the processing and subcellular localization of the lysosomal protease cathepsin D.

The expression, processing, and intracellular localization of cathepsin D (CD), an endosomal-lysosomal protease involved in malignancy, were studied in rat embryo fibroblasts transformed with an active mutant of c-Ha-ras oncogene. The pattern of the processed molecular forms of CD, comprising two single-chain mature forms of 45 and 43 kDa and two double-chain mature forms of 34 + 9 kDa and 30 + 14 kDa, expressed by the parental cell line was similar to that found in normal rat liver cells. By contrast, in the ras-transfected counterpart this pattern was profoundly altered in that the 45 kDa species was much less represented and the 30 + 14 kDa species virtually absent. In both untransformed and ras-transformed cells the conversion of proCD into mature forms was not inhibited by ammonium chloride, which is known to increase the intravacuolar pH of post-Golgi compartments. Yet, this drug induced the accumulation of the 43 and 45 kDa molecular forms of mature CD in ras-transformed cells and of the 34 kDa molecule in untransformed cells. As compared to controls, in ras-transformed fibroblasts vacuolar compartments containing CD were reduced in number and mostly located toward the periphery of the cell. This contrasted with the perinuclear distribution of CD-positive granules in untransformed cells. Serum deprivation did not affect the growth, nor the intra- and extracellular accumulation of CD activity in ras-transformed cultures, while it blocked the growth and strongly stimulated the accumulation of CD in the medium in cultures of control fibroblasts. Altogether these data are indicative for a crucial role of ras GTPase in the regulation of the transport between post-Golgi organelles.

Choroid plexus carcinoma: report of one case with favourable response to treatment.

Choroid plexus carcinoma (CPC) is a rare tumor with usually severe prognosis, whose optimal treatment has not yet been established. The exact role of complete surgical resection, chemotherapy, and radiotherapy has been debated but not clarified. We report one girl with CPC diagnosed at age 3 months and apparently cured with minimal surgical resection, chemotherapy, and delayed irradiation. At the age of 8 years, she is well, with minor psychomotor retardation and growth hormone deficiency as the only sequelae.

Langerhans cell histiocytosis and acute leukemia: unusual association in two cases.

Langerhans cell histiocytosis (LCH) is a non-malignant disorder, whether localized or disseminated, and usually has a favourable prognosis. A possible relationship between LCH and neoplastic diseases has not been assessed up to now even if a few cases have been recorded. We report two new cases of acute leukemia in children with LCH. The first child had acute lymphoblastic leukemia after untreated LCH; the second developed acute promyelocytic leukemia after LCH treated with vinblastine and etoposide. To our knowledge, this is the first case of secondary leukemia after exposure to an epipodophyllotoxin derivative in a child with benign disease. Cooperative studies of large numbers of LCH patients are needed to evaluate a possible association between LCH and acute leukemia, and to identify common risk factors or predisposing agents if such be present.

[The direct and computed radiographic assessment of vertebral locations in children with acute lymphatic leukemia]. / Valutazione radiografica diretta e computerizzata delle localizzazioni vertebrali nei bambini affetti da leucemia linfatica acuta.

The children affected with acute lymphoblastic leukemia (ALL) often exhibit secondary lesions of the spine. The diagnosis of spinal involvement is currently made by means of conventional radiography in postero-anterior and lateral views. The osteolytic lesions of the vertebral body present with collapse of the vertebral plates in a wide range of severity. Body evaluation is usually made by comparison with the adjacent vertebrae. Since leukemia is a systemic disease, several vertebrae are possibly involved in each case. In the attempt to develop a more sensitive method, which is less dependent on observers' evaluation, a quantitative and comparative analysis of vertebral bodies was performed. The radiographs in lateral view of the dorsal and lumbar spine of 14 children with ALL were analyzed: previous radiological reports suggested the lesion of one or more vertebral bodies. The area of each vertebral body was measured and digitalized by means of a backlighted graphic table and of a software developed to this purpose. The criteria to define the collapse of a vertebral body were the ratio between areas of adjacent vertebral bodies, in conformity to the anatomic and radiographic principle that, in the dorsal and lumbar spine, the body of a normal vertebra is equal to or bigger than that of the upper one. The data obtained by quantitative analysis were compared with conventional radiologic reports. A hundred and fifty-five vertebrae were analyzed by computerized analysis; 17 (10.9%) vertebrae, undetected at conventional analysis, were collapsed. This method allows a more precise diagnosis of collapsed vertebral lesions; its accuracy can be improved with further development of digital technology.

Partial response after intensive chemotherapy for adrenal cortical carcinoma in a child.

Adrenocortical carcinoma (ACC) in childhood is a rare tumor with high fatality rate. Available reports provide event free survival rates ranging between 10 to 50%. Optimal treatment has not yet been established; surgery plays a major role, and the value of adjuvant chemotherapy needs to be evaluated further, especially in children who develop recurrent disease and those with metastases at diagnosis. Optimal therapy of ACC has not been established. Surgery has been curative after complete tumor resection. Children with inoperable, recurrent and metastatic ACC have been treated with O,P'DDD, with response rates ranging from 10 to 60% in different series [7,11-20]. Radiotherapy [21] and other anti-cancer drugs have been used [4-22] but their efficacy has not been established. Combination chemotherapy containing oncovin, cisPlatinum, epipodophyllotoxin and cyclophosphamide (OPEC) produced regression of metastatic ACC in a 5-year-old male [23]. We report one girl with relapsed disseminated ACC who showed good, even if temporary, control of the disease, with disappearance of lung, liver and spleen metastases, and marked reduction of the adrenal mass, following combined chemotherapy according to the "eight-drugs-in-one-day" protocol.

Prospective randomized comparison of toxicity of two prophylactic regimens of cotrimoxazole in leukemic children.

Cotrimoxazole is currently used for Pneumocystis carinii pneumonia prophylaxis in leukemic children. The former regimen of continuous administration was recently replaced by intermittent administration. The antifolic activity of cotrimoxazole could theoretically enhance that of methotrexate, also administered to leukemic children. We report on a prospective, randomized study to compare two different regimens--continuous vs. 3 days a week--of cotrimoxazole prophylaxis. The aim of the study was to evaluate the toxicity, assuming that both regimens are equally effective to prevent P. carinii pneumonia. Seventy-seven leukemic children were enrolled; 67 were evaluable, 35 from arm A (continuous), 32 from arm B (intermittent cotrimoxazole administration). The conclusion was that long-term maintenance chemotherapy with antimetabolites produced lower levels of folate but normal levels of vitamin B12 in leukemic children. This pattern did not vary between the continuous and the 3-days-a-week administration of cotrimoxazole prophylaxis. Thus it seems hypothesizable that the antimetabolic activity of methotrexate alone exceeds that of cotrimoxazole.

Clotting abnormalities in children during maintenance chemotherapy for acute lymphoblastic leukemia.

BACKGROUND: Many of the drugs used in the treatment of acute lymphoblastic leukemia in children may induce modifications in different organs and functions. Following the observation of a recurrent, mild delay in the prothrombin time in ALL children during maintenance chemotherapy, we explored the main parameters of the clotting function. METHODS: 17 children with acute lymphoblastic leukemia were studied during maintenance chemotherapy for clotting function screening evaluation; 15 healthy children, matched for age and sex, were used as controls. RESULTS: A uniform pattern of slight prolongation of the prothrombin time with significantly reduced levels of factors VII, IX, and a trend toward reduced activity of factor X was observed in the absence of any demonstrable anticoagulant factor. CONCLUSIONS: Antileukemic maintenance chemotherapy is associated with a subclinical modification of the clotting parameters that is not responsible for hemorrhagic diathesis. Long-term administration of anti-metabolites (6-mercaptopurine and methotrexate) could be responsible for this reversible impairment.

Severe acute encephalopathy following inadvertent intrathecal doxorubicin administration.

In a female with acute lymphoblastic leukemia, inadvertent doxorubicin administration intrathecally caused severe, life-threatening, acute encephalopathy with high-pressure hydrocephalus. Ventriculo-peritoneal shunting led to complete reversal of hydrocephalus with progressive disappearance of the acute encephalopathy.

[Aerobic bacterial flora in cutaneous lesions and in venous catheters of severely burned patients]. / La flora batterica aerobica nelle lesioni cutanee e nei cateteri venosi dei grandi ustionati.

Bearing in mind the complexity of the topic and its variability owing to the progress made in antibiotic management, and the development of many concepts concerning the pathogenesis and biochemistry of major burns, the already massive literature is supplemented by the addition of relatively recent data to enable comparisons to be made with regard to the quality and frequency of isolation of the bacterial flora observed in such patients, and above all their sensitivity to currently employed antibiotics. The investigation was conducted on patients admitted to the Turin CTO Major Burns Centre between 1972 and 1977. Initially (1972-1975), a microbiological examination was made of purulent secretions from wounds. Subsequently, management was prevalently directed to the early excision of injured surfaces, and attention was therefore directed to the indwelling venous catheters used in treatment and parenteral alimentation. In cases examined in parallel, moreover, there was often a substantial similarity between wound and catheter flora, and when only one species was present in the wounds, the catheter was often sterile. Furthermore, numerous data were collected from antibiograms relating to the most frequently encountered micro-organisms. These usually displayed wide resistance spectra, especially with respect to the most commonly used of historically oldest antibiotics, whereas their resistance to those recently introduced was generally lower. The question of provenance (from the patient himself, the hospital or its medical and paramedical staff) is also examined. Reference is made to a point that has recently become important in the treatment of burns, namely the ascertainment of the degree of contamination not only on the surface, but also in the immediate sub-surface of the lesions, so as to permit a suitable excision of the eschar and skin transplantation. When a sufficient number of findings exist to support this new concept, it will certainly give rise to further studies and research aimed at bringing new, important data to this so rich and multiform topic.

[Behavior of complement factors and plasma proteins in burns]. / Comportamento di alcuni fattori del complemento e di alcune proteine plasmatiche nella malattia da ustione.

The behaviour of three complement components (C3, C4 and C3 activator), alpha 1, alpha 2, IgA, IgG, IgM, total proteins, and gamma globulins was followed 114 patients at the C.T.O. Turin, Burns Centre with burns covering from 15% to over 70% of the body surface. Forty-two died within a relatively short time. In the remaining 72, the parameters were studied almost daily for over 30 days, or even until a final cure was obtained. The complement data and, more particularly, the distinct increased in alpha-globulins made it clear that burns can be acute inflammations. In addition, initial immune depression is followed by a prompt response of the complement system (responsible for aspecific immunity). That this change is vital in the progress of the disease may be deduced from the fact that complement component levels were constantly below normal in the patients who died.