The behavior of single crystals of NaCl: Ca2+, Mn2+ exposed to gamma rays

The behavior of single crystals of NaCl: Ca(2+), Mn(2+) exposed to gamma rays was explored for its potential usage as a dosimeter. The study was focused to the effect of dose and dose rate. The crystals were analyzed using thermoluminescence (TL). The productions of irradiation defects in the solid were correlated with the glow curve. F-centers were measured as function of the dose. The bleaching of the F-centers produced a decrease of the peak of the glow curve. The results showed that the response is linear in an interval up to 60 Gy.

Phosphatidylinositol 3-kinase and ERK are required for NF-kappaB activation but not for phagocytosis

The molecular events that transduce signals from Fc receptors to the various cellular responses are still poorly defined. We have investigated the role of phosphatidylinositol 3-kinase (PI 3-K) and extracellular signal-regulated kinase (ERK) in gene activation and phagocytosis in monocytes. In the THP-1 monocytic cell line, cross-linking of Fc receptors by immune complexes results in activation of the transcription factor NF-kappaB, via activation of ERK. Activation of both ERK and NF-kappaB was blocked by wortmannin and LY294002, specific inhibitors of PI 3-K. Wortmannin also inhibited the Fc receptor-mediated increase in the cytosolic calcium concentration, but it did not block immunoglobulin G (IgG)-mediated phagocytosis. In addition, the ERK inhibitor PD98059 did not block phagocytosis of IgG-coated erythrocytes. Both the increase in the cytosolic calcium concentration and phagocytosis depend on an active actin cytoskeleton, as indicated by the total lack of both responses after treatment with cytochalasin B. In contrast, cytochalasin B did not affect Fc receptor-mediated activation of NF-kappaB. These results identify PI 3-K and ERK as important signaling molecules in the Fc receptor signal transduction pathway of monocytes, which leads to the nucleus for gene activation. These results also suggest that, in contrast to other cell types, unstimulated monocytes do not require PI 3-K and ERK for phagocytosis.

[Surveillance of surgical wound infections. 18-month experience in the Instituto Nacional de Cancerología]

OBJECTIVE

To calculate the surgical site infection (SSI) rates with a surgical prospective surveillance program and postdischarge follow-up.

MATERIAL AND METHODS

During a 18 months period (01/01/93 to 04/30/94), a surgical wound surveillance program followed on the surgeries practiced at the National Institute of Cancerology, a referral center situated in Mexico City. Rates per 100 surgeries were calculated for the surgical services and for each of the wound class strata. The SS's were classified according to the 1992 Center for Disease Control definitions for surgical infections.

RESULTS

Three thousand, three hundred and severity-two surgeries were assessed; 313 were diagnosed as infected: 140 (44.7%) were superficial incisional, 137 (43.7%) were deep incisional and 36 (11.5%) were organ and space infections. The SSI rate for this period was 9.28%; for the clean, clean-contaminated, contaminated and dirty surgeries the rates were 7.35, 10.5, 17.3 and 21.5% respectively. The rates for each service were: gastroenterology, 14.13%; breast tumors, 11.08%; mixed tumors, 10.98%; gynecology, 9.06%; urology, 7.38%; head and neck, 7.13%, and thoracic surgery, 1.81%. On average SSI were detected at 11.6 +/- 6.23 days, eighty-five (27.16%) were diagnosed while the patient was in-hospital, the remaining 228 (72.84%) were detected after discharge. In 134 (42.8%) patients a culture was obtained. The bacteria most frequently found were: E. coli, 38 (22.5%); coagulase negative Staphylococci, 23 (13.6%); Pseudomonas sp., 22 (13%); S. aureus, 16 (9.4%); and Enterococcus, 13 (7.7%).

CONCLUSIONS

The prospective surveillance program with a follow-up for 30 days increased by 400% the chance to identify a SSI. The SSI rate for clean and clean-contaminated surgeries are above the rates reported in the literature.

Fcgamma receptor-mediated mitogen-activated protein kinase activation in monocytes is independent of Ras

Receptors for the Fc portion of immunoglobulin molecules (FcR) present on leukocyte cell membranes mediate a large number of cellular responses that are very important in host defense, including phagocytosis, cell cytotoxicity, production and secretion of inflammatory mediators, and modulation of the immune response. Cross-linking of FcR with immune complexes leads, first to activation of protein-tyrosine kinases. The molecular events that follow and that transduce signals from these receptors to the nucleus are still poorly defined. We have investigated the signal transduction pathway from Fc receptors that leads to gene activation and production of cytokines in monocytes. Cross-linking of FcR, on the THP-1 monocytic cell line, by immune complexes resulted in both activation of the transcription factor NF-kappaB and interleukin 1 production. These responses were completely blocked by tyrosine kinase inhibitors. In contrast, expression of dominant negative mutants of Ras and Raf-1, in these cells, did not have any effect on FcR-mediated nuclear factor activation, suggesting that the mitogen-activated protein kinase (MAPK) signaling pathway was not used by these receptors. However, MAPK activation was easily detected by in vitro kinase assays, after FcR cross-linking with immune complexes. Using the specific MAPK/extracellular signal-regulated kinase kinase (MAPK kinase) inhibitor PD98059, we found that MAPK activation is necessary for FcR-dependent activation of the nuclear factor NF-kappaB. These results strongly suggest that the signaling pathway from Fc receptors leading to expression of different genes important to leukocyte biology, initiates with tyrosine kinases and requires MAPK activation; but in contrast to other tyrosine kinase receptors, FcR-mediated MAPK activation does not involve Ras and Raf.

Signal transduction by immunoglobulin Fc receptors

Receptors for the Fc portion of immunoglobulin molecules (FcR) present on leukocyte cell membranes mediate a large number of cellular responses that are very important in host defense. Cross-linking of FcR by immune complexes leads to functions such as phagocytosis, cell cytotoxicity, production and secretion of inflammatory mediators, and modulation of the immune response. Molecular characterization of FcRs indicates the existence of several types of these receptors, which seem to be redundant in their cell distribution and function. There is a great deal of interest in understanding how these various receptors signal the cell to respond in different ways during inflammation and the immune response. Previous studies indicate that FcR signaling shares elements with the T and B cell antigen receptors. Signaling is initiated in all of them by activation of tyrosine kinases of the Src and ZAP-70 families. Subsequent events, which vary depending on the cell type and receptor involved, include activation of other enzymes such as phospholipase Cgamma1, phosphatidylinositol-3-kinase, and mitogen-activated protein kinase. Several recent lines of research, including studies of phagocytosis by FcR-transfected cells, antibody-dependent cytotoxicity by natural killer cells, mast cell degranulation, and FcR-deficient mice, have given us new insights on the signal transduction pathways activated by FcRs. This review describes the advances in these areas and presents a general model for FcR-mediated signaling.

Chemotherapy-associated oral mucosal lesions in patients with leukaemia or lymphoma

In order to determine the incidence rate of oral lesions associated with chemotherapy, as well as well as its association with clinical and laboratory parameters and potential risk factors, 50 in-patients with non-Hodgkin's lymphoma or leukaemia under chemotherapy were followed from January 1993 to May 1994. Basal and weekly oral examinations were performed. Clinical and laboratory data were registered. Wilcoxon's rank sum test, chi square test, univariate and multivariate logistic regression analyses were used, 36 individuals with leukaemia and 14 with non-Hodgkin's lymphoma were followed for 158 weeks; mean age was 33 years (range 15-85). Oral lesion incidence rate was 45/100 patients-week. Exfoliative cheilitis and infections (herpes and candidosis) were the most common oral complications, followed by haemorrhagic lesions and mucositis. Haemorrhagic lesions correlated with thrombocytopenia (RR = 30.5). Etoposide administration (RR = 8.6), alkylating agents (RR = 15.6), a prior course of chemotherapy (RR = 23.2) and neutropenia (RR = 4.16) were predictors of mucositis. Oral lesions were a common complication in this study, and a possible association of mucositis with several factors is suggested.

[A surveillance program for surgical wound infections at the National Institute of Cancerology of Mexico]

OBJECTIVES

To evaluate the results of a prospective wound infection surveillance program during its first semester of operation, and to analyse the risk factors associated to wound infection.

METHODS AND DESIGN

From January 01 to June 30 1993, 1103 surgeries were prospectively followed. The incidence rates of infection were calculated and a case control analysis was done to evaluate the associated risk factors to POWI (postoperative wound infection).

SETTING

An oncological tertiary-care center.

RESULTS

The POWI rate was 9.0 per 100 surgeries. By univariate analysis the associated risk factors were: obesity (OR = 2.07 CI95% = 1.19-3.64), one drainage (OR = 2.10 CI = 1.33-3.31), two drainages (OR = 3.14 CI = 1.85-5.26), length of stay of the drainage (patients with wound infection: 15.2 +/- 6.7 days vs. patients without wound infection: 8.2 +/- 6.6 days), duration of operation (patients with wound infection: 188 +/- 163 minutes vs. patients without wound infection: 122 +/- 127 minutes) and duration of preoperative hospitalization (patients with wound infection: 2.9 +/- 6.4 days vs. patients without wound infection 1.5 +/- 3.0 days). The associated risk factors by regression analysis were: obesity (OR = 1.93 CI = 1.08-3.43), two drainages (OR = 2.09 CI = 1.03-4.05) duration of operation > = 120 minutes (OR = 1.96 CI = 1.00-3.86) and duration of preoperative hospitalization (OR = 1.03 CI = 1.00-1.09).

CONCLUSIONS

The program showed a previous under-reporting of POWI from 4.2-4.8 per 100 surgeries in the previous seven years to 9.0 in the first semester of operation. It also identified the associated risk factors to POWI in our institution.

[AIDS and neoplasms in Mexico]

OBJECTIVE

To describe the epidemiological profile of AIDS and malignancies in Mexico.

MATERIAL AND METHODS

The study population included a group of AIDS patients seen at four National Institutes of Health and one at a general hospital in Mexico City, from 1983 to 1992. Demographic, clinical and laboratory information was obtained.

RESULTS

A total of 202 patients were studied; 199 men and three women. The mean age was of 34.5 years (range 18-67 years). Kaposi's sarcoma was the most frequent malignancy, with 166 cases, followed by non-Hodgkin's lymphoma, with 33 cases. The three women had non-Hodgkin's lymphoma, one of them associated with cervical carcinoma. Rectal cancer was present in three cases.

DISCUSSION

The spectrum of AIDS-associated malignancies in Mexico is similar to that described in other populations. The early diagnosis of this complication is necessary, as well as the search for therapeutic actions to prevent severe immunosuppression and the consequent appearance of malignancies.

[The risk factors in primary bacteremias: a case-control study]

Nosocomial bacteremias are a important cause of mobility and mortality for hospitalized patients which, in addition, generate additional and elevated costs to the institutions. Its frequency has increased in the last year in relation to a greater number of patients, many of them immunosuppressed, which are submitted to invasive procedures. In this study, we analyzed the primary nosocomial bacteremias which occurred in our institution, carrying out a comparative case and control study in order to find the main risk factors which condition their occurrence. In a period of 42 months, 83 episodes of nosocomial primary bacteremias were detected. These represented an incidence of 8 per 1000 of patients which left the hospital and with a clear rising incidence in the last six months. In the Intensive Care Unit (ICU) a greater rate was found per sector (21.3 x 1000). The predominating agents were S. epidermidis, enterobacteremia, S. aureus and enteroccocci. Of the 15 possible risk factors analyzed by multiple regression, those significant were over two weeks of hospital stay and the use of parenteral feeding. These results make it imperative to reinforce control measures in the preparation of parental feeding solutions as in patients with prolonged hospital stay, especially in the ICU.

Clinical patterns of diarrhea in AIDS: etiology and prognosis

OBJECTIVE

To define the etiology and prognosis of diarrhea (acute, intermittent or chronic) in AIDS patients.

DESIGN

A retrospective analysis of patients with AIDS and diarrhea. Patterns of diarrhea were defined a priori. Endpoints of interest were etiology, rate of response to therapy, development of chronic diarrhea, and survival probability. Data were analyzed by means of univariate and multivariate tests (chi-square, ANOVA, Student's t test, Kaplan-Meier, logrank and logistic regression analysis).

SETTING

A 170-bed tertiary-care university hospital which is one of the three most important referral centers for AIDS patients in Mexico City.

PATIENTS

The records of the 279 AIDS patients admitted to the hospital between 1983 and 1989 were reviewed; 225 cases were suitable for analysis.

MEASUREMENTS

The presence of a diarrheal episode, the diagnostic studies to which the patient was submitted, the etiology, the response to therapy and the survival time from the point at which the diarrhea started were all recorded. Diarrheal patterns were stratified by clinical patterns and outcomes compared. Possible clinical predictors of chronic diarrhea were analyzed.

RESULTS

Seventy seven percent of the patients suffered at least one diarrheal episode. Diarrhea was in fact the most common AIDS-related complication in our series, and in 51% of the total cases (114/225), it was the first HIV-related symptom. The diarrheal pattern was intermittent in 47% of the cases, chronic in 36% and acute in the remaining 17%. An etiology was established in only 59% of the episodes, and Cryptosporidium was the etiologic agent most frequently isolated (30%). Other opportunistic pathogens prevailed in chronic and intermittent diarrheas. Chronic persistent diarrhea was related to a lower survival probability (60% at one year vs 90% for intermittent and 95% for acute diarrhea, p < 0.0001). When the performance of different diagnostic studies was analyzed, the combination of stool culture, serial parasitic examination and sigmoidoscopy with biopsies provided a high diagnostic accuracy (59%). Regardless of etiology, the rate of therapeutic success was directly related to the previous duration of diarrhea and the absolute lymphocyte count (p < 0.01).

CONCLUSIONS

There are three distinct diarrheal patterns common to AIDS patients. Although the etiologic agents do not vary significantly, each pattern has unique characteristics regarding the timing of presentation, their survival and therapeutic success rate. Such differences should be taken into account when therapeutic trials are designed.

Distribution of mast cells in the tracheal tissue components of the guinea pig and its bearing on the Schultz-Dale reaction

The distribution of mast cells in the tracheal tissue components and its bearing on anaphylaxis was studied in the guinea pig. According to a statistical analysis (Nested ANOVA) the density found in the tissue elements showed the following gradation (mean +/- SE): muscle (299.7 +/- 61.6 cells/mm3) < serosa (802.7 +/- 131.2 cells/mm3) < submucosa (24283.5 +/- 2549.2) < mucosa (48066.4 cells/mm3 +/- 7837.4). Regardless of their location in tissue elements, the cell density in a zone far from the muscle was larger than in a zone close to the muscle. Considering the histamine release capability of mast cells, the density found either in muscle or in its surroundings does not account for the mediation theory unless some postulates ad hoc are introduced. A direct biophysical mechanism is possibly involved. Another alternative is a reflex to histamine, since there is preponderant location of mast cells in mucosa and submucosa.

Probability of mast cells to mediate anaphylaxis in skeletal muscle

Are there enough mast cells in denervated skeletal muscle to account for autopharmacological mediation of the antigen potentials (APs) elicited by microtaps? Through rough qualitative estimations, some authors have suggested a positive answer to this question. However, in view of measurements performed in this investigation of both the density of mast cells and the diffusion coefficient of antigens, the probability of such mediated effects was found to be relatively low: P = 0.016 for egg albumin and P = 0.004 for ferritin. Therefore, most APs induced by microtaps should be attributed to the direct effect of antigen over the sensitized muscle fibers. Yet, both the density of mast cells found in this work and the known amount of histamine they are capable of releasing when challenged with antigen, support the hypothesis regarding the involvement of these cells when antigen is massively superfused so as to induce Schultz-Dale reactions in muscle strips. Under this circumstance, the direct and mediated mechanisms may coexist.

Changes in mast-cell distribution in skeletal muscle after denervation

Motor nerves are known to govern the structure of skeletal muscle. In the normal guinea pig diaphragmatic muscle, we found that mast cells were predominantly located in the central tendon. Following denervation, these cells became more numerous in the muscle itself than in the tendon. Therefore, nervous trophic influences are exerted on other tissue elements besides those which sustain transmission and contraction. Ascertaining mast-cell distribution in biopsies may help to elucidate denervation effects in motor neuron disease.

[Usefulness and risks of transtracheal aspiration in the diagnosis of pulmonary infections]

OBJECTIVE

To define the diagnostic usefulness and the risks of the transtracheal aspirate in a group of patients studied at the National Institute of Nutrition in Mexico City.

DESIGN

It is a retrospective and descriptive analysis of a group of patients in whom a transtracheal aspiration (TTA) was performed due to suspicion of pulmonary infection. The study period was from 1983 to 1987.

PATIENTS

On the study period 137 patients were submitted to a TTA; the clinical files of 126 of the cases were considered suitable for analysis.

RESULTS

The procedure was performed because of a suspected bacterial pneumonia in 80% of the cases, and to study an interstitial infiltrate or pulmonary nodules in 14% and 6%, respectively. In the cases in which a bacterial pneumonia was suspected, the TTA had a sensitivity of 77% and a specificity of 95% when compared against a group of clinical, radiologic and microbiological data. Sensitivity increased to 84% when the patients who received antibiotics prior to the procedure were excluded. The specificity of the sputum's culture was sensibly less in this same group of patients. The TTA proved to be of value in five of nine pulmonary tuberculosis, two of three pulmonary mycoses and three of seven P. carinii pneumonias. Adverse events were noted in 6.3% of the cases; none of them was fatal, and specific corrective measures were necessary in only two patients.

CONCLUSIONS

Our results agree with previous reports related to the usefulness of the TTA on patients with a suspected bacterial pneumonia. Our specificity is higher than that seen by other authors: we believe this is due to the low incidence of chronic respiratory diseases in the patients who attend our hospital. Transtracheal aspirate can be a valuable alternative in the diagnosis of non-bacterial pulmonary infections when the elective procedures cannot be performed. A modification on the technique is proposed to increase its usefulness in patients with interstitial pneumonia.

Diagnostic laparotomy in fever of unknown origin

Twenty five consecutive patients with fever of unknown origin (FUO) who underwent diagnostic laparatomy (DL) are reviewed. There were 14 females and 11 males, with a mean age of 34 years. The main symptoms and signs besides fever were malaise, weight loss, varied abdominal complaints, peripheral lymph nodes enlargement, hepatomegaly and splenomegaly. The main laboratory abnormalities were: anemia, leukocytosis, and mild alterations in liver function tests. CT scan was performed in 14 patients: hepatomegaly, splenomegaly and or retroperitoneal nodes were found in 10 of them. During laparotomy, an extensive exploration of intra-abdominal organs was performed, taking multiple biopsies for histopathologic and microbiologic analysis. Splenectomy was performed in 17 patients, prophylactic appendectomy in four, and cholecistectomy in one. Laparotomy was useful to establish a diagnosis in 64 percent of cases. The most frequently diagnosed pathologies were lymphoma and tuberculosis. Postoperative morbidity was 12% and mortality was 4%. Mean follow-up was 29 months. When preoperative data were analyzed, no predictive factors were found for a laparotomy with diagnostic success. It is concluded that DL is a useful last-step procedure in the diagnostic work-up for patients with FUO.