Prevalence, topographic and morphometric features of femoral cam-type deformity: changes in relation to age and gender.

Femoroacetabular impingement (FAI) syndrome is a frequent cause of pain and in recent years considered to be a precursor of premature hip osteoarthritis. The structural abnormalities which characterize FAI syndrome, such as the cam-type deformity, are associated with morphological alterations that may lead to hip osteoarthritis. The aim of this study was to determine the prevalence and topographic and morphometric features of the cam deformity in a series of 326 femur specimens obtained from a Mexican population, as well as changes in prevalence in relation to age and gender. The specimens were subdivided into groups according to gender and age. A standardized photograph of the proximal femur of each specimen was taken, and the photograph was used to determine the alpha angle using a computer program; the location of the lesion was determined by quadrant and the morphometric characteristics were determined by direct observation. The overall prevalence of cam deformities in the femur specimens was 29.8 % (97/326), with a prevalence by gender of 35.2 % (64/182) in men and 22.9 % (33/144) in women. The mean alpha angle was 54.6° ± 8.5° in all of the osteological specimens and 65.6° ± 7.5° in those specimens exhibiting a cam deformity. Cam deformities were found topographically in the anterior-superior quadrant of the femoral head-neck junction in 86.6 % (84/97) of the femurs. Deformities were found in 28.2 % of the right femurs and 31.3 % of the left femurs. The prevalence of cam deformity was higher in the femur specimens of young men and in those of middle-aged and older women. There were no significant differences in this deformity in relation to the alpha angle according to age and gender.

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.

Dependence of irradiation temperature in the response of iron salts.

A potential dosimeter based on aqueous frozen solutions and solid-state salt are presented for the evaluation of the energy transferred during the interaction of high-energy radiation with matter at low temperature. The foundation of these dosimeters, both the solid state and the frozen solutions, is based on the measurement of the change of the iron oxidation state. The systems were irradiated with gamma radiation at different doses (up to 10 MGy), and at different temperatures (from 77 to 298 K). The irradiated samples were analysed by UV-spectroscopy and Mössbauer spectroscopy. A theoretical model was developed for the chemical reactions system. This model reproduces the experimental effects produced by the irradiation in aqueous solutions of ferrous salt. The results showed that the response of the dosimeters depends on the irradiation temperature. At low-radiation doses, the response was linear. In particular, this work can be applied to low-temperature dosimetry can be specially applied to simulation experiments of extraterrestrial bodies, as well as in general to space research.

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]. / Vigilancia de las infecciones de herida quirúrgica. Experiencia de 18 meses en el 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.

Frequency of intestinal parasites in adult cancer patients in Mexico.

Approximately 28% of the Mexican population has intestinal parasites. Oncologic patients receiving chemotherapy should have a coproparasitoscopic study to avoid disseminated parasitic infections. The frequency of intestinal parasites, including Cryptosporidium and Isospora, was evaluated in 100 diarrheic (DS) and 100 formed stools (FS) from adult patients recently diagnosed with cancer, using wet mounts stained with Kinyoun, saccharose and ZnSO4 procedures stained with Lugol's iodine. Seven patients with DS and three with FS had more than one parasite. Pathogenic intestinal parasites were seen in 26% of DS and 15% of FS. Of the frequent parasites, Entamoeba histolytica was found in 12 DS and in 2 FS (p = 0.01), Giardia lamblia in three DS and six FS and Hymenolepis nana in eight DS and 10 FS. Other pathogenic parasites were found only in DS: Cryptosporidium sp. in five patients, Ascaris lumbricoides in two, Strongyloides stercoralis in two and Isospora sp. in one. Cryptosporidium and Isospora were only identified by wet mounts stained with Kinyoun while other parasites were identified by flotation procedures. Since six (3%) of our patients had coccidia, the laboratory must perform special techniques for their detection. In epidemiologic settings where there is a high prevalence of intestinal parasitic infections the coproparasitoscopic studies should be performed and antiparasitic treatment provided before starting chemotherapy.

Toxoplasmosis of the central nervous system in patients with AIDS in Mexico.

Toxoplasmosis of the central nervous system (CNS) is the most common cause of intracerebral lesions in patients with AIDS. It is now standard clinical practice to treat empirically, based on clinical and radiographic findings, and to perform a biopsy of the lesion only in those patients who fail to have a clinical and radiographic response after two weeks of therapy. This study describes the presentation and response to therapy of central nervous system toxoplasmosis in patients with AIDS at a private practice in Mexico City. A retrospective chart and radiology review of all patients with AIDS treated empirically for toxoplasmosis between 1988 and 1993 was performed. A total of 177 patients with AIDS were seen, nine (5.1%) had toxoplasmosis. Patients with toxoplasmosis were males with a median age of 39 years (range 26 - 65). In two patients, toxoplamosis of the CNS was the initial manifestation of HIV infection, all others had a prior diagnosis of AIDS with a mean of 10 months between their first AIDS defining event and the diagnosis of toxoplasmosis. The median CD4+ T-cell count at the time of the diagnosis of toxoplamsosis was 78 cells/microL. Most patients had headache associated with other focal neurological symptoms such as hemiplegia (2), hemiparesis (2) or seizures (4). Only 4 out of 9 patients had fever as part of their initial clinical presentation. Serum IgG antibodies against Toxoplasma gondii were positive in 6 out of 7 patients tested, while IgM antibodies were negative in all patients. On imaging studies (Computerized Tomography or Magnetic Resonance Imaging), 4 patients had a single lesion while the rest had two or more lesions. Two patients were initially treated with pyrimethamine/sulfadiazine and were later changed to pyrimethamine/clindamycin, which was the treatment given from the beginning to all other patients. One patient died of an intralesional hemorrhage two weeks after the diagnosis despite adequate therapy. The probability of surviving 6 months after the diagnosis of toxoplasmosis was 60%. The findings of these authors are similar to those reported in other series where toxoplasmosis of the CNS is a late complication of HIV infection associated with a CD4+ cell count of < 100 cells/microL. However, survival was short in spite of a good response to therapy.

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]. / Programa de vigilancia de infección de herida quirúrgica en el Instituto Nacional de Cancerología de México.

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]. / SIDA y neoplasias en México.

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.

Cancer of the mobile tongue in Mexico. A retrospective study of 170 patients.

Histological reports of 170 patients with cancer of the mobile tongue between 1977 and 1989 were identified at the Instituto Nacional de Cancerología (INCan), in Mexico City. Demographic, clinical and histological information was retrospectively reviewed. Chi-square, Student's t-test and Wilcoxon rank-sum test were applied for comparisons, and Kaplan-Meier curves, log-rank test and Cox proportional hazards for survival analysis. Of the 161 patients with mobile tongue squamous cell carcinoma (MTSCC), 104 (65%) were males and 57 (35%) were females. The mean age was 60 years old (range 19-91). T1 and T2 lesions comprised 35%, T3 and T4 lesions 65%. There was a statistically significant association between size of the tumour and lymph node involvement (P < 0.0001). The proportion of cases with advanced disease was 80% for males and 57% for females (P = 0.008). The 5-year survival rate was 16% (CI 10.2-22.8%). Cancer of the mobile tongue in Mexico still has a poor prognosis. Efforts should be made to reduce the delay in diagnosis of MTSCC, in order to increase the cure rates and improve the quality of life of the patients.

[The risk factors in primary bacteremias: a case-control study]. / Factores der riesgo en bacteremias primarias: un estudio de casos y controles.

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.

Experience of an intravenous therapy team at the Instituto Nacional de Cancerología (Mexico) with a long-lasting, low-cost silastic venous catheter.

Means of vascular access are fundamental in the management of cancer. However, since current intravenous devices for long-term treatment are expensive and necessitate a high degree of education among medical personnel, in developing countries they are impractical for use in most of the population. We describe the use of a nontunneled, low-cost, long-lasting Silastic catheter (LLSC), cared for by an intravenous therapy team (IVTT), in 462 patients with cancer. The rate of infectious complications was 0.66 infections per 1,000 catheter-days, which is as low as that reported in association with other catheters in developed countries. Neutropenia and skin and/or soft-tissue infections were significant risk factors associated with LLSC-related infections. We believe that use of this catheter may be an alternative for patients with cancer who need chemotherapy, as long as an IVTT is established for its care. Our experience could be useful for practitioners in countries with similar socioeconomic characteristics.

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.

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.

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.

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]. / Utilidad y riesgos del aspirado transtraqueal en el diagnóstico de infecciones pulmonares.

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.