A pseudoinverse for Frank's formula

In a previous communication, it has been argued that in the Frank-Bilby equation and in the o-lattice equations a pseudoinverse must be used when the reduced displacement-field matrices are not invertible. Here an explicit expression for the pseudoinverse of Frank's formula is derived using a direct vector approach.

Phylogeography and regional endemism of a passively dispersing zooplankter: mitochondrial DNA variation in rotifer resting egg banks

We investigated the phylogeography of the salt water rotifer Brachionus plicatilis, a cyclical parthenogen with passive dispersal mechanisms, using resting eggs recovered from saline lake sediments. Individual resting eggs were obtained from a large selection of lakes which were representative of five endorheic basins and the chain of coastal ponds in the Iberian Peninsula. The novel use of resting eggs allows the integration of seasonal and annual variations as well as the impact of stochastic effects such as drift and local extinction. A 653 bp fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene was sequenced from 98 eggs. Our results revealed a deep phylogeographical structure in this species, with a division into two main lineages with distinct geographical distributions, which probably diverged at the beginning of the Pleistocene period. Most of the mitochondrial DNA haplotypes were restricted to single lakes. Nested clade analysis supported Early Pleistocene fragmentation of populations, low gene flow and some long-distance colonization. These conclusions contrast strongly with previous ideas on rotifer biogeography and this pattern is consistent with a recolonization of the Iberian Peninsula from two glacial refugia. The results provide new insights into the processes responsible for the genetic diversification of passive dispersers, a life-history trait typical of zooplanktonic biotas.

Tegumentary leishmaniasis in Northern Argentina: distribution of infection and disease, in three municipalities of Salta, 1990-1992

This work describes the epidemiological pattern of tegumentary leishmaniasis in an area north of Salta, Argentina. The prevalence and incidence were estimated by means of a cross-sectional study and two follow-up studies during two consecutive years. The Montenegro Skin Test (MST) was administered to 7336 subjects at baseline. The prevalence and incidence between 1990 and 1992 of infection (MST reactive) was 38 per mil persons and 4.5 per mil persons/year respectively. The prevalence and incidence of tegumentary leishmaniasis (presence of clinical signs) was 1.8 per mil and 0.8 per mil persons/year, respectively. A physical examination performed on 264 patients with MST reactive during three years revealed that 130 cases (49.2%) had some evident sign of infection (scar and/or lesion), with a clinical presentation compatible with leishmaniasis. Our study demonstrated that after the epidemic outbreak of 1985 the transmission in the study area returned to endemic levels in 1992, and also demonstrated the presence of the asymptomatic infection in the area.

[Bone scintigraphy findings in patients with recently diagnosed adenocarcinoma of the prostate: relationship with prostate specific antigen levels]

BACKGROUND AND OBJECTIVES

Although it has been suggested that bone scintigraphy (BS) may not be necessary in patients with prostate adenocarcinoma (PA) and normal prostate specific antigen (PSA) plasma levels, controversy still remains. The objective of the study was to evaluate the existing relationship between PSA plasma levels and BS findings in patients with a recently diagnosed PA in order to assess whether BS may be omitted on the basis of the PSA levels in these patients.

METHODS

The 475 patients (70+/-7 years old) consecutively diagnosed of PA between 1994 and 1998 in our institution made up the study population. PSA plasmatic levels were determined and BS was performed (body planar study after 99mTc-methyl diphosphonate 900 MBq administration) in all the patients.

RESULTS

In 362 patients (76.2%), BS was negative, in 108 (22.7%) positive and undetermined in the remaining 5 patients (1.1%). The mean PSA level in the whole study population was 74+/-267 ng/ml (range 0.4-4.200) and was higher in patients with positive GO (218+/-512 vs 31+/-89, p<0,0001). As PSA increased, the rate of patients with positive BS was significantly higher, this being 0%, 16.4%, 9.7%, 14.0%, 31.0% and 48.3% in patients with PSA 4, 4.1-10; 10.1-20; 20.1-30; 30.1-40, and >40 ng/ml, respectively (p<0.0001). In patients with positive BS, the PSA levels were 20 and 10 ng/ml in 30.6% and 18.6% of the patients, respectively.

CONCLUSION

According to our experience, there is a significant association between PSA plasma levels and the BS results in patients with recently diagnosed PA. However, a significant proportion of patients with bone metastasis have normal PSA levels, and therefore BS should be performed in all patients with recently diagnosed PA regardless of the PSA levels.

Economic impact of HIV protease inhibitor therapy in the global use of health-care resources

OBJECTIVE

To evaluate the clinical and economical impact of the introduction of HIV protease inhibitor (PI) therapy in the current clinical care of HIV-infected patients.

METHODS

Cohort study with 155 HIV-infected patients with a full year of follow-up before and after the introduction of PI by June 1998. The setting was a large urban tertiary teaching hospital in Madrid, Spain. The main outcomes measures were clinical and immunological evolution, pharmacy, out-patient, emergency room and in-patient medical costs evaluated by diagnostic-related group classification, and the global economic costs of clinical care in HIV-infected patients (AIDS and non-AIDS).

RESULTS

The cost of PI therapy was compensated fully by savings related to reduction of the number, length and severity of hospital admissions in AIDS cases. In contrast, more modest clinical effects with increased costs were observed in non-AIDS cases. Globally, there was an increase of about 20% in the total health-care costs of HIV-infected patients (P < 0.01).

CONCLUSIONS

PI therapy is highly cost-effective in AIDS patients. Its value in less severely immunosuppressed patients requires further evaluation.

[Results of myocardial scintigraphy with 99mTc-tetrofosmin and dipyridamole administration in patients diagnosed of microvascular angina]

The objective of the study was to evaluate the results of the myocardial scintigraphy with 99mTc-tetrofosmin (Tc-Tf) and pharmacological stimulation with dipyridamole in patients diagnosed of microvascular angina. The study population is made up of 50 patients discharged with the diagnosis of microvascular angina who had undergone Tc-Tf-dipyridamole. Clinical and electrical positivity appeared in 40% and 12% of the patients, respectively. Myocardial perfusion defects were found in 35 patients (70%), and were reversible in 21 (60%), fixed in 11 (21%), and combined in 3 (9%). Abnormalities were inferior, anteroseptal and lateral in 21, 18, and 2 patients, respectively. Patients with a positive exercise treadmill test, compared with those with a negative one, had more frequent perfusion abnormalities (91% vs 50%, p = 0.0327) and myocardial ischemia (64% vs 20%, p = 0.392). Women, in comparison with men, had angina (56% vs 22%, p = 0.013), and anteroseptal perfusion abnormalities (26% vs 4%, p = 0.028) more frequently. On the contrary, men had inferior perfusion abnormalities more frequently (57% vs 30%, p = 0.057). Thus, Tc-Tf-dipyridamole shows perfusion abnormalities in 70% of patients with microvascular angina (91% in patients with a positive exercise treadmill test). Scintigraphic pattern may be partially conditioned by gender in these patients.

Intra-abdominal desmoplastic small round-cell tumor: a rare cause of peritoneal malignancy in young people

We report the CT and pathological findings of an intra-abdominal desmoplastic small round-cell tumor in a young man. Computed tomography showed an extensive peritoneal and mesenteric disease with gross bulky masses, direct liver invasion, and lymph node involvement. This entity should be considered in the differential diagnosis of a young male patient presenting with features of widespread peritoneal malignant disease.

Systemic lupus erythematosus: mortality and survival in Argentina. A multicenter study

OBJECTIVE

To analyze the factors associated with mortality, survival and causes of death in patients with systemic lupus erythematosus (SLE) in Argentina.

PATIENTS AND METHOD

A series of 366 patients with SLE (45 men and 321 women), mean age 29 y (range 11-70 y) and mean disease duration 6 y, was evaluated from 1990 to 1998. A total of 57 clinical, serological and therapeutic variables were studied.

RESULTS

Five- and 10-year survival was 91% and 85% respectively. Forty four patients died (12%): 54% due to sepsis and 32% due to active SLE. Mortality risk factors included heart involvement CRR 3.82), hyperlipidemia (RR 2.72), renal damage (RR 2. 62), infections (RR 2.44), lung disease (RR 2.20) and myositis (RR 2. 07). High-dose prednisone (RR 3.4) or cyclophosphamide (RR 9.19) treatments increased the risk of sepsis (P=0.003) as a cause of death. However, corticosteroids, antimalarial agents and accumulated cyclophosphamide doses proved to be protective factors in overall mortality figures (RR <1).

CONCLUSIONS

The main risk factors of death in SLE were heart involvement, hyperlipidemia and renal damage. Treatment with steroids, antimalarial agents and cyclophosphamide improved survival. High-dose corticosteroids and cyclophosphamide were associated with sepsis as a cause of death.

Prognostic value of the quantified expression of p185 in non-small cell lung cancer

BACKGROUND

We sought to assess the relationship between tissue concentration of erb -b-2 or neu oncogene-encoded protein (p185(neu)) with overall survival in patients with non-small cell lung cancer.

METHODS

Levels of protein p185(neu) were determined in 102 patients with the diagnosis of non-small cell lung cancer. Concentration of p185(neu) protein was determined by using enzyme immunoassay and evaluated by using several variables. The relative prognostic importance of this marker and its influence on other prognostic factors was evaluated by using the Cox regression model.

RESULTS

The mean p185(neu) value in these samples was 250 +/- 200 U/mg (95% confidence interval, 210-290). This distinguished two groups within the tumoral population: those with less than 350 U/mg and those with 350 U/mg or greater (80th percentile). Multivariable analysis established an independent prognostic value for protein p185(neu). Patients with p185(neu) values of the 80th percentile or greater had a risk of death that was 2.11-fold (95% confidence interval, 1.10-4.05) that of patients with values of less than 350 U/mg (P =.03), and increases in the neu oncogene of 100 U/mg increased the probability of death by 17% (P =.02; 95% confidence interval, 1.04-1.31).

CONCLUSION

This study shows that the p185(neu) expression is an objective and comparable variable for the assessment of phenotypic aggressivity in non-small cell lung cancer, and in the future, it could be included in daily clinical practice.

[The use of biological markers in the diagnosis and follow-up of patients with multiple sclerosis. Test of five fluids]

PATIENTS AND METHODS

We studied five biological fluids which were easily accessible to immunological examination (cerebrospinal fluid, plasma, tears, saliva and urine) in 25 patients with multiple sclerosis, clinically definite according to the criteria of Cleveland, Ohio (1991) and tabulated according to the Kurztke's expanded disability status scale. The samples were obtained simultaneously during a clinical bout of the disease before any pharmacological or immunosuppressive treatment had been given.

RESULTS

The soluble interleukin-2 levels were significantly raised in at least three of these fluids--always absent from the urine--when compared with normal controls. The sensitivity and specificity of this determination for diagnosis of the condition was greater than that of other immunochemical parameters--oligoclonal distribution of immunoglobulins (specifically of IgG), imbalance of the light Kappa and Lambda chains--and physiological studies (evoked potentials). The dosification and quantification of basic myelin protein of the central nervous system, rich in citruline in the urine, may be a parameter of progressiveness.

CONCLUSION

This methodology (five humours test) may be used to establish an earlier, more certain diagnosis of multiple sclerosis and also monitor its biological activity together with nuclear magnetic resonance with intravenous contrast.

[PET detection of recurring rectal adenocarcinoma in an unusual location. Case report]

A rare pattern of colon cancer recurrence is presented. A 63-year-old man underwent surgical resection after diagnosis of colon cancer. The postsurgical-pathologic examination showed a stage II colon cancer (MAC B2). Six courses of adjuvant chemotherapy (Mayo protocol) were started within four weeks of surgery. During follow-up, serial serum carcinoembryonic antigen levels became progressively elevated in an otherwise asymptomatic patient who showed no signs of recurrence in any of the conventional imaging tests performed (chest X-ray, abdominal ultrasound, and abdominal CT-scan). Positive findings suggesting lymph node mediastinal metastases were present in the PET scan. Surgical resection and pathologic examination demonstrated metastases of colon adenocarcinoma.

[Control of the transmission of Trypanosoma cruzi in Argentina 1999]

Approximately 2 million people in Argentina are infected with Trypanosoma cruzi, the etiologic agent of Chagas disease, thereby constituting the major tropical disease in the country. As in other six Southern Cone countries, Triatoma infestans is the only or major vector of T. cruzi among human and domestic animals. In Argentina, a vertically structured National Chagas Control Program was established in 1962. Such a program pursued the elimination of domestic and peri-domestic populations of T. infestans through insecticidal spraying, and the serological control of blood donors to prevent transfusion-related infections. This program strongly reduced the nation-wide serological prevalence of T. cruzi in the population. For example, in 18 or 20 year-old men drafted into military service, the seroprevalence decreased from 10.1% in 1964 for those who had been born in 1944 to 1.9% in 1993 for those born in 1975. However, the vertical strategy failed to reach and sustain the surveillance phase in widespread rural areas with disperse populations due to its intrinsic limitations and the reduced priority level assigned to rural health programs. An alternative, horizontally-structured control strategy of T. infestans was developed and assayed in the Province of Santiago del Estero between 1985-1989, and 1991-1992. The projects demonstrated that insecticidal spraying carried out with community participation combined effectiveness and commitment in such a way as to produce a strong impact on house reinfestation and the extension of the area under entomological surveillance. This experience has been transferred in a chain of responsibilities to the personnel of the National Chagas Control Program, using participating workshops, procedural guidelines, and practical training. This personnel transferred the strategy using similar methods to the field health care agents and volunteers chosen by their own communities (community leaders). After the workshops, the leaders received all the materials needed to install and develop the ongoing surveillance activities: third generation pyrethroid insecticides, manuals, hand-operated sprayers, and sensor boxes to detect domiciliary infestations. From 1993 to 1998, a total of 15,000 health care agents or community leaders were trained. A total of 675,000 houses were sprayed with residual insecticides in the attack phase, and 850,000 houses entered the surveillance phase. This is the first time that such large coverage has been accomplished in Argentina. The network of laboratories installed a quality assurance program to current serological procedures applied to blood donors, organ transplant, and the detection and treatment of newborns to women sero-reactive for T. cruzi in Argentina. We expect to interrupt the vector-mediated transmission of T. cruzi in the next 18 months, but the sustainability of such a program depends on, at least, additional work with the community to achieve a change of attitudes and practices related to house infestation for the next 10 years. A social effort will be needed to cover those expenses, but the expected economic returns exceed largely the cost of any such program, as suggested by cost-benefit studies. To illustrate, the annual treatment costs of one Chagas patient can help maintain 25 households free from triatomine bugs in Argentina.

Differential Th1/Th2 cytokine patterns in chronic arthritis: interferon gamma is highly expressed in synovium of rheumatoid arthritis compared with seronegative spondyloarthropathies

OBJECTIVE

To investigate possible differences in Th1 and Th2 cytokine mRNA expression in the synovial tissue (ST) of patients with rheumatoid arthritis (RA) and seronegative spondyloarthropathies (SpA) with diagnostic and/or pathogenic interest.

METHODS

Eleven RA patients and 14 SpA patients (10 with undifferentiated spondyloarthropathy (USpA), two with ankylosing spondylitis (AS) and two with psoriatic arthritis (PsA)) were included. Th1 (interferon gamma, interleukin 2) and Th2 (interleukin 4, interleukin 5 and interleukin 10) cytokine mRNA levels from arthritic knee ST were quantified by using an optimised polymerase chain reaction method with a computerised analysis system. Protein levels of proinflammatory cytokines (interleukin 1, tumour necrosis factor alpha and interleukin 6) in synovial fluid were quantified with a specific ELISA test.

RESULTS

Th1 cytokines were detected in all of RA ST samples in contrast with 58% (interferon gamma) and 71% (interleukin 2) of SpA samples. Th2 cytokines were expressed in 90% of RA ST samples, but the findings in SpA were interleukin 10 in 90%, interleukin 4 in 60% and interleukin 5 in 40% of ST samples. However, when the mRNA levels of each cytokine were quantified and corrected for T cell mRNA levels, only interferon gamma levels were significantly higher in RA than in SpA (p<0.003). Thus, the Th1/Th2 cytokine ratio in RA was fivefold that of SpA. Synovial fluid interleukin 1beta concentrations were higher in RA than in SpA (p<0. 05); there were also higher synovial fluid levels of tumour necrosis factor alpha in RA than in SpA, but without statistical significance.

CONCLUSION

This study has detected both Th1 and Th2 cytokine gene expression in ST from RA and SpA patients. Synovium interferon gamma mRNA levels and SF interleukin 1beta protein levels were significantly higher in RA than in SpA, so reflecting the known proinflammatory activity of interferon gamma through macrophage activation. Thus, the Th1 (interferon gamma)/Th2 (interleukin 4) ratio is significantly higher in RA than in SpA ST. These data confirm previous studies on ST Th1/Th2 balance in RA and extend previous work in comparing ST RA with subgroups of SpA distinct of ReA.