Protists and other organisms on a minute snail periostracum / Protistas e outros organismos em um pequeno periostracum de caracol

Abstract Since the foundation of the Malacological Center in 1980, Universidad Centro Americana (UCA), Managua-Nicaragua, has been monitoring and collecting the marine, terrestrial, fluvial and lake mollusk population of the country. Many specimens have been photographed by Scanning Electronic Microscope (SEM), and in one of these, observation of the hairy periostracum reveals a seemingly thriving population of minute protists in possible symbiosis with their host. Adequate magnification and comparison with previous studies allowed the determination of these hosts as diatoms, testaceous amoebae, yeast, phacus, spores and other undetermined organisms which occur in tropical forests on rocks, trees and leaves. Here illustrated are diatoms and other organisms detected for the first time on the periostracum of a tropical rainforest mollusk.

Resumo Desde a fundação do Centro Malacológico em 1980, a Universidad Central Americana (UCA), Manágua-Nicarágua, vem acompanhando e coletando a população de moluscos marinhos, terrestres, fluviais e lagoas do país. Muitos espécimes foram fotografados pelo microscópio eletrônico de varredura (SEM) e, em um deles, a observação do periostracum peludo revela uma população aparentemente próspera de protistas de minuto em possível simbiose com o hospedeiro. A ampliação adequada e a comparação com estudos anteriores permitem a determinação dessas diatomáceas, amebas testaceas, leveduras, phacus, esporos e outros organismos indeterminados que ocorrem em florestas tropicais em rochas, árvores e folhas. Aqui estão as diatomeas e outros organismos pela primeira vez detectados no periostracum de um molusco tropical.

Protists and other organisms on a minute snail periostracum.

Since the foundation of the Malacological Center in 1980, Universidad Centro Americana (UCA), Managua-Nicaragua, has been monitoring and collecting the marine, terrestrial, fluvial and lake mollusk population of the country. Many specimens have been photographed by Scanning Electronic Microscope (SEM), and in one of these, observation of the hairy periostracum reveals a seemingly thriving population of minute protists in possible symbiosis with their host. Adequate magnification and comparison with previous studies allowed the determination of these hosts as diatoms, testaceous amoebae, yeast, phacus, spores and other undetermined organisms which occur in tropical forests on rocks, trees and leaves. Here illustrated are diatoms and other organisms detected for the first time on the periostracum of a tropical rainforest mollusk.

Protists and other organisms on a minute snail periostracum

Abstract Since the foundation of the Malacological Center in 1980, Universidad Centro Americana (UCA), Managua-Nicaragua, has been monitoring and collecting the marine, terrestrial, fluvial and lake mollusk population of the country. Many specimens have been photographed by Scanning Electronic Microscope (SEM), and in one of these, observation of the hairy periostracum reveals a seemingly thriving population of minute protists in possible symbiosis with their host. Adequate magnification and comparison with previous studies allowed the determination of these hosts as diatoms, testaceous amoebae, yeast, phacus, spores and other undetermined organisms which occur in tropical forests on rocks, trees and leaves. Here illustrated are diatoms and other organisms detected for the first time on the periostracum of a tropical rainforest mollusk.

Resumo Desde a fundação do Centro Malacológico em 1980, a Universidad Central Americana (UCA), Manágua-Nicarágua, vem acompanhando e coletando a população de moluscos marinhos, terrestres, fluviais e lagoas do país. Muitos espécimes foram fotografados pelo microscópio eletrônico de varredura (SEM) e, em um deles, a observação do periostracum peludo revela uma população aparentemente próspera de protistas de minuto em possível simbiose com o hospedeiro. A ampliação adequada e a comparação com estudos anteriores permitem a determinação dessas diatomáceas, amebas testaceas, leveduras, phacus, esporos e outros organismos indeterminados que ocorrem em florestas tropicais em rochas, árvores e folhas. Aqui estão as diatomeas e outros organismos pela primeira vez detectados no periostracum de um molusco tropical.

Determinants of the geographic variation of invasive cervical cancer in Costa Rica.

The incidence of cervical cancer in Costa Rica is about twice as high in the coastal regions as in the interior. To study these regional variations, we used data from a 1986-1987 case-control study of 192 Costa Rican women with invasive cervical cancer and 372 controls. Risk factors identified included the following: The study participant's (1) number of sexual partners, (2) age at first sexual intercourse, (3) number of live births, (4) presence of type 16/18 human papillomavirus (HPV) DNA, (5) venereal disease (VD) history, (6) Pap smear history, and (7) socioeconomic status. The adjusted relative risks (RR) and 95% confidence intervals (CI) for each of these risk factors were as follows: (1) > or = 4 vs. 1 sexual partner: RR = 2.0, 95% CI = 1.1-3.5; (2) age of initiation < or = 15 vs. > or = 18 years: RR = 1.5, 95% CI = 0.9-2.5; (3) > or = 6 vs. < or = 1 live birth: RR = 1.7, 95% CI = 0.7-3.9; (4) HPV 16/18 DNA in cervix: RR = 2.8, 95% CI = 1.9-4.2; (5) VD history: RR = 2.2, 95% CI = 1.2-4.0; (6) no Pap smear: RR = 2.4, 95% CI = 1.5-3.8; and (7) low socioeconomic status: RR = 2.0, 95% CI = 1.2-3.2. The population-attributable risks related to HPV detection, four or more sexual partners, six or more live births, no prior Pap smear, and low socioeconomic status were 39%, 38%, 29%, 23%, and 22%, respectively. Several of the sexual and reproductive risk factors were relatively more prevalent in the high-risk region, but Pap screening and detection of HPV were equally prevalent in the high-risk and low-risk regions. Though differences in screening quality (laboratory and follow-up) may have been involved, we conclude that the observed regional differences reflect behavioral more than screening differences. This suggests that screening programs should be more aggressive in the high-risk area, given the more frequent occurrence of the disease there. Failure to detect a higher prevalence of HPV in the high-risk region could reflect weaknesses in the in situ hybridization test employed. Alternatively, cofactors may have to be present in order for HPV to exert its role in cervical carcinogenesis.

Ovarian low-grade stromal sarcoma with thecomatous features: a critical reappraisal of the so-called "malignant thecoma".

A case of low-grade ovarian stromal sarcoma in a postmenopausal woman is described. Although pelvic recurrences of the tumor followed 5 and 7 years after the original surgery, the patient has remained well and without evidence of tumor 3 years since the last operation. Histopathologic, electronmicroscopic, and hormonal studies are described. There was evidence of estrogenic stimulation by the theca elements of the tumor in this patient. Cases previously reported in the world literature as malignant thecoma were analyzed, and most of them were considered inadequately documented; indeed most of them were probably either sarcomatoid granulosa cell tumors, stromal sarcomas, or fibrosarcomas. If a thecoma ever becomes malignant, the tumor cells dedifferentiate so that they cannot be recognized any longer as theca cells; instead, they proliferate as a stromal sarcoma or fibrosarcoma. It is proposed, therefore, that the term "malignant thecoma" not be used. On the other hand, very rare malignant ovarian stromal tumors do exist, consisting of undifferentiated stromal cells, fibroblasts, and theca cells, which can show evidence of hormonal activity.

Brenner tumor and mucinous cystadenoma of borderline malignancy in a patient with Turner's syndrome.

A 64-year-old woman with a 45,X karyotype and Turner's syndrome and recent onset of right lower quadrant pain was found to have a mucinous cystadenoma with focal areas of borderline malignancy and a typical Brenner tumor in the right adnexa. Ovarian tumors in patients with a 45,X karyotype and Turner's syndrome are extremely rare. The present paper is the first report of concurrence of these 2 tumors in an affected individual. The simultaneous occurrence and intimate admixture of these tumors in a patient believed to be devoid of germ cells would seem to favor a common histogenesis from the germinal epithelium.

Observations on the surface area of the abnormal transformation zone associated with intraepithelial and early invasive squamous cell lesions of the cervix.

The apparent area of the abnormal transformation zone (TZ) of the cervix was measured in a total of 104 patients by a simple method with the use of the 1 and 5 mm. diameter circle in the center of the field of the Leisegang colposcope and the field of the colposcope itself. The visible area (mean +/- S.E.M.) of the abnormal TZ for five patients with microinvasive or occult carcinoma of the cervix (180.8 mm.2 +/- 62.2) was significantly larger (p less than 0.01) than that of 64 patients with major intraepithelial lesions (62.5 sq. mm.2 +/- 7.3) and 35 patients with minor intraepithelial lesions (45.8 sq. mm.2 +/- 11.7). The visible area of the abnormal TZ measured over 40 mm.2 in each of the five patients with invasive lesions but in only 42 of 99 (42%) patients with intraepithelial lesions. The TZ extended into the endocervical canal and could not be fully visualized in four (80%) of the patients with invasive lesions, 24 (38%) of patients with major intraepithelial lesions, and 11 (31%) of patients with minor intraepithelial lesions. The implications of these findings are discussed.

Some observations on the value of endocervical curettage performed as an integral part of colposcopic examination of patients with abnormal cervical cytology.

A total of 259 patients underwent endocervical curettage as an integral part of colposcopic examination of patients with abnormal cervical cytology. The transformation zone was entirely visualized in 140 patients (54.1 per cent), and, in 8.6 per cent of this group, the endocervical curettings were abnormal. On no occasion did the endocervical curettage harbor the worst lesion when compared to the histology of the ectocervical biopsy, cone biopsy, and hysterectomy specimens. In 117 patients (45.2 per cent), the transformation zone could not be visualized in its entirety, and in 57.3 per cent the endocervical curettings were abnormal. In one patient of this group invasive carcinoma was present in the endocervical curettage, and in another patient invasive carcinoma was present in both the ectocervical biopsy and the endocervical curettage. Thus, when the entire transformation zone is not visualized in its entirety or at all, endocervical curettage appears to be of value since a frank invasive carcinoma may be diagnosed and a cone biopsy avoided.

An immunofluorescent study of basement membranes in squamous cell carcinoma of the cervix, vagina, and vulva.

Basement membranes of 33 samples of in situ or invasive squamous cell carcinomas of the cervix uteri, vagina, and vulva were studied by defined immunofluorescence technics. Pooled serum from patients with bullous pemphigoid, containing specific antibody to squamous epithelial basement membrane, was utilized. Essentially normal basement membranes were found in all cases of in situ carcinoma and in 18 cases of invasive carcinoma. Basement membranes appeared poorly formed in three specimens with invasion and were absent in the remaining three. These findings support the premise that penetration of the basement membrane is not a valid criterion for distinguishing in situ from invasive squamous cell carcinoma.