PubMed Health⌕ Search

Biomedical subjects

A D Hernandez

Publications and source records attributed to A D Hernandez.

At least 19 recordsLinked to original sources
PubMed2006

Composition and diversity patterns in metazoan parasite communities and anthropogenic disturbance in stream ecosystems.

The composition and diversity of metazoan parasite communities in naturally depauperate ecosystems are rarely studied. This study describes the composition of helminth endoparasite communities infecting fish that are part of naturally acidic stream ecosystems in the coastal-plains region of the State of New Jersey (USA) known as the Pinelands, and compares the diversity of parasites between six streams that differ in anthropogenic disturbance. A total of 514 fish were examined representing 6 species native but restricted to the Pinelands region, 5 species native and widespread throughout the region and State, and 6 species introduced to the Pinelands and State. Fish (prevalence: 78%) were infected with 18 helminth endoparasite species. In most streams, prevalence of infection, mean abundance, and total number of individuals for the 5 most common parasites were higher in pirate perch, a native fish species. The diversity of helminth endoparasite communities measured as species richness and Shannon index was higher in degraded streams, and especially in native or introduced fish at these sites. Parasite diversity was positively correlated with anthropogenic disturbance, which was measured by water pH, water conductance, and the proportion of agricultural and developed land surrounding streams. Helminth community composition included parasites intimately tied to trophic interactions in food webs, and disturbance to these ecosystems results in changes to these communities. Understanding structure and function of animal communities from these naturally depauperate ecosystems is important before continued anthropogenic changes result in the extirpation or extinction of their unique fauna.

Animals↗
PubMed1998

Seasonal patterns in the biology of Eubothrium salvelini infecting brook trout in a creek in lower Michigan.

A total of 392 brook trout, Salvelinus fontinalis, and 211 slimy sculpin, Cottus cognatus, was examined for Eubothrium salvelini (Cestoda) from May 1995 through September 1996 from Sweetwater Creek, Michigan. No seasonal pattern in prevalence, intensity, and abundance of parasites in trout and sculpin was determined. However a seasonal pattern in the length and percent gravid E. salvelini in brook trout suggests that recruitment of this parasite occurs during late summer and early fall. During this time the procercoid in the copepod intermediate host is expected to be available in the environment for fish to recruit, but a total of 6,399 copepods was not infected. Gravid worms were not found in slimy sculpin, suggesting it is a paratenic or dead-end host. Detailed studies on the biology of parasites may be more indicative of seasonal transmission patterns than studies that only measure prevalence, abundance, and intensity.

Animals↗
PubMed1997

Parasites of the deepwater sculpin, Myoxocephalus thompsoni (Cottidae), from Lake Michigan and Lake Huron.

A total of 190 deepwater sculpins, Myoxocephalus thompsoni, collected in 1995 from Michigan waters of Lake Michigan and Lake Huron was examined for parasites. Five parasite species occurred in sculpins from Lake Michigan with Echinorhynchus salmonis being most common. Six parasite species infected sculpins from Lake Huron, with Haplonema sp. the most common. Haplonema sp. is the only gravid helminth species reported from deepwater sculpins. Pleistophora sp. and Trichodina sp. infected sculpins from Lake Huron and Lake Michigan. Parasite species richness for sculpins at the 3 locations ranged from 5 to 6; mean values ranged from 1.18 to 1.39 for examined fish. The restricted diet of deepwater sculpin, which may be related to the depth of its habitat, appears to determine its helminth fauna. Deepwater sculpin may be an important transport host for E. salmonis, Cyathocephalus truncatus, and Eubothrium salvelini to lake trout and burbot that commonly feed on them.

Acanthocephala↗
PubMed1997

Transrectal ultrasound versus digital rectal examination for the staging of carcinoma of the prostate: results of a prospective, multi-institutional trial.

PURPOSE: We determined the accuracy of transrectal ultrasonography versus digital rectal examination in staging the local extent of biopsy proved carcinoma of the prostate. MATERIALS AND METHODS: A National Institutes of Health funded network was developed to perform prospective, multi-institutional trials. A total of 386 patients judged by the investigators to be candidates for radical prostatectomy underwent transrectal ultrasonography with recording of data according to a numerical analog for construction of receiver operating characteristic curves. The results of digital rectal examination were similarly recorded. After radical prostatectomy whole mount histology was performed on all surgical specimens, and pathological findings were correlated with preoperative transrectal ultrasound and digital rectal examination results. RESULTS: The calculated area under the curve for transrectal ultrasound in predicting extracapsular tumor extension was 0.69 compared to 0.72 for digital rectal examination (p = 0.64), while that for predicting seminal vesicle invasion was 0.74 and 0.69, respectively (p = 0.36). There was a nonstatistically significant trend for improved accuracy of both examinations as tumor volume increased. Transrectal ultrasound was more accurate for staging posterior cancers than for those in the anterior portion of the prostate. CONCLUSIONS: Neither transrectal ultrasound nor digital rectal examination proved to be superior to each other for staging the local extent of prostate cancer. No imaging modality or examination that depends on gross architectural changes is likely to have a high degree of accuracy in detecting microscopic extension of extracapsular tumor frequently observed in radical prostatectomy specimens.

Adenocarcinoma↗
PubMed1995

Host grooming and the transmission strategy of Heligmosomoides polygyrus.

Grooming behavior may play a part in the transmission of the gastrointestinal nematode, Heligomosomoides polygyrus in the mouse host. After infective larvae are placed on individually housed mice, significantly higher numbers of adult worms were recovered from the small intestine of mice that were allowed to self-groom when compared to infection levels in mice that had been fitted with Elizabethan collars to prevent self-grooming. Larvae placed on a single mouse housed with 3 other untreated mice resulted in all mice in the group becoming infected, suggesting that allogrooming may also be important in parasite transmission. A significantly higher percentage of larvae nictate on rough surfaces such as damp peat moss substrate when compared to smooth surfaces such as 0.5% agarose. Mice exposed to larvae placed on peat moss substrate have significantly higher infection levels when compared to mice exposed to larvae on a 0.5% agarose substratum, suggesting that natural transmission of infective L3 larvae in mice may be dependent on a substratum type that allows nictation behavior. A significantly higher percentage of worms were attracted to mouse urine and mouse and rat epidermal lipids when compared to deionized water controls in an in vitro preference assay, suggesting an attraction to host-specific signals. These results support the hypothesis that transmission of this parasite is an active process involving movement of the infective larvae of H. polygyrus into the host's active space where they are ingested during grooming behavior.

Animals↗
PubMed1992

A screening study of prostate cancer in high risk families.

In a study of the familial risk of prostate cancer 17 sets of 2 brothers with prostate cancer were identified. A total of 34 first-degree relatives of these probands (sons and brothers, 55 to 80 years old) underwent an intensive screening examination that included prostate specific antigen, digital rectal examination, transrectal ultrasound and systematic as well as clinically directed core needle biopsies. Previously unsuspected and clinically relevant cancers were found in 8 men (24%), compared to the approximately 1 expected (p less than 0.01). Of these cancers 2 were detected by the systematic biopsies. This study emphasizes the importance of thorough screening in first-degree relatives of prostate cancer patients.

Aged↗
PubMed1991

Long-term follow-up after radical prostatectomy. Identification of prognostic variables.

We report one of the largest series of patients treated by radical prostatectomy followed for a minimum of 10 years. The tumor-free survival rate at 10 years seems superior to that achieved with alternative methods of treatment. Pathologic stage, DNA histograms, and tumor grade all correlate with prognosis but none is sufficiently powerful as an independent factor to allow selection of patients for surgery. Although a survival benefit has not been demonstrated, adjuvant treatment such as postoperative irradiation or early hormonal therapy may be indicated in patients with established poor prognostic factors.

Follow-Up Studies↗
PubMed1990

Ultrasonographic characteristics of the seminal vesicles after ejaculation.

A total of 12 men from a sperm donor bank underwent transrectal ultrasonography before and after ejaculation to investigate possible changes that could influence interpretation of seminal vesicle ultrasonography. The mean length of the seminal vesicles was 2.98 cm. before and 2.95 cm. after ejaculation. The anteroposterior diameter decreased only from 0.59 to 0.52 cm. Minimal differences were noted between the right and left seminal vesicles, and the greatest variation in size in an individual was only 3 mm. These results indicate that interpretation of seminal vesicle anatomy as seen by ultrasonography does not depend upon the temporal relationship to ejaculation.

Adult↗
PubMed1990

A controlled study of the argon beam coagulator for partial nephrectomy.

An argon beam coagulator was evaluated in 25 canine partial nephrectomies to determine its hemostatic capabilities, safety and degree of thermal injury to renal parenchyma. Comparison was made with a control group of seven partial nephrectomies performed by standard technique. In both groups the procedure was performed without renal cooling or clamping of the renal artery. The argon beam coagulator was operated with a power output of 130 watts. Mean operative time for partial nephrectomy was 22 minutes in the control group versus 10 minutes when the argon coagulator was used (p less than 0.001). Mean blood loss was 276 cc by standard technique but only 135 cc with the argon coagulator (p less than 0.001). A regular eschar with a mean depth of tissue necrosis of 2.4 mm. was observed with the argon coagulator.

Animals↗
PubMed1990

Transrectal ultrasonography for the early detection and staging of prostate cancer.

Relatively recent changes and improvements in equipment have vastly increased image resolution for transrectal ultrasonography of the prostate. The expanded use of transrectal ultrasonography has greatly furthered knowledge of prostate zonal anatomy and permitted clinical evaluation of internal prostate architecture. The technique is operator dependent, as the quality of the results is related directly to that person's knowledge and experience. The significant majority of prostate cancers originate from the peripheral zone. Palpable stage B nodules characteristically have a hypoechoic appearance. There is disagreement about the tumor characteristics that cause hypoechogenicity, but large tumors may obscure the normal prostate anatomy and appear isoechoic because of the lack of contrast with surrounding prostate tissue. The transition zone of the prostate is the origin of benign prostatic hyperplasia and almost 20 per cent of prostate cancers. These tumors probably correspond to most stage A lesions. Transrectal ultrasonography is less accurate in identifying transition zone tumors because of the mixed echogenicity of the transition zone, interference from prostatic calculi or calcified corpora amylacea, and poorer image resolution in this area. Studies evaluating the use of transrectal ultrasonography for early detection of prostate cancer generally have shown a twofold increase in the detection rate compared with digital rectal examination. However, the decreased morbidity and expense of transrectal prostate biopsy using an automatic gun device have increased the frequency of biopsy in ultrasound-examined patients compared with those historically evaluated by digital rectal examination. The increased detection rate may in part be a function of the increased use of biopsies, independent of other factors. Transrectal ultrasonography rarely detects cancer in patient with normal digital rectal examination and a normal serum prostate-specific antigen level. Transrectal ultrasonography may be capable of identifying early capsular penetration or seminal vesicle invasion in some patients with known prostate cancer. However, its superiority to digital rectal examination for this purpose has not been demonstrated unequivocally. Ultrasonography does allow directed biopsies of the seminal vesicles or other suspect areas, and this may be helpful in staging the disease. The use of transrectal ultrasonography in prostate cancer has evolved rapidly, and changes in technology antiquate reports within a few years.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1989

Cutaneous cryptococcosis.

Cutaneous cryptococcosis occurs in 10 to 15% of patients with cryptococcosis. Because the cutaneous crytpococcosis may precede clinical signs of central nervous system disease, early recognition may lead to more successful outcomes. This article reviews the mycology, epidemiology, pathology, clinical manifestations, and treatment of this disease, focusing primarily on the cutaneous aspects.

Acquired Immunodeficiency Syndrome↗
PubMed1988

The immune response of guinea-pigs to type II collagen: poor cross-reactivity with homologous type II collagen accounts for resistance to collagen-induced arthritis.

In order to determine the susceptibility of guinea-pigs to collagen-induced arthritis (CIA), Hartley and Strain 13 guinea-pigs were immunized with heterologous or homologous type II collagen. None of the animals developed CIA. Because immunity to type II collagen plays a critical role in CIA, we characterized the guinea-pig's immune response to determine the basis for this resistance. Guinea-pigs develop cellular and humoral reactivity to heterologous type II collagen similar to that of CIA-susceptible rats. The reactions distinguish type I from type II collagen but not among several heterologous type II collagens. The cell-mediated immune (CMI) response was specific for determinants on the primary amino acid structure of collagen, whether native or denatured collagen was used for immunization; however, the humoral response was specific for the form of the molecule used for immunization. Guinea-pigs differ from CIA-susceptible rats in that immunization with homologous or heterologous type II collagen fails to induce significant cross-reactive immunity with the homologous antigen. A transient arthritis could be induced in animals immunized with heterologous type II collagen by injecting them intra-articularly with heterologous but not with homologous type II collagen. Our results show that the disparity between immunity to type II collagen and the susceptibility to develop CIA in guinea-pigs is due to their poor cross-reactive immune response to autologous type II collagen.

Animals↗
PubMed1987

Immunolocalization of collagenase inhibitor in normal skin and basal cell carcinoma.

Human collagenase inhibitor is a ubiquitous glycoprotein capable of blocking the action of several connective tissue metalloproteinases, including collagenase, gelatinase, and proteoglycanase. The action of this proteinase inhibitor may constitute a pivotal step in the control of connective tissue matrix degradation. Using monospecific antibody to collagenase inhibitor as an immunocytochemical probe, we determined its in vivo localization in normal human skin and in a pathologic state, the altered connective tissue stroma surrounding basal cell carcinoma. Collagenase inhibitor was localized diffusely throughout the dermis and appeared to be associated with the extracellular matrix components, both in normal skin and in basal cell carcinoma. Intense staining was present in the stroma surrounding islands of basal cell carcinoma. The increased amounts of collagenase inhibitor may be a result of its production by stromal fibroblasts stimulated by cytokines of tumor or inflammatory cell origin. These findings are similar to those previously described for dermal collagenase. Both collagenase inhibitor and collagenase itself appear to be normal components of the extracellular matrix, and amounts of both are increased in the altered stroma surrounding neoplastic cells. Thus we suggest that the balance of degradative proteinase(s) to specific inhibitor may be an important factor in determining the composition of the extracellular matrix.

Antibodies, Monoclonal↗
PubMed1986

Trichophyton mentagrophytes spores differ from mycelia in their ability to induce pustules and activate complement.

To determine whether the morphology of dermatophytes plays a role in the clinical manifestation of dermatophytosis, we isolated spores and mycelia from colonies of killed Trichophyton mentagrophytes and tested their ability to induce gross and microscopic cutaneous changes when applied to guinea pig skin. The skin of normal guinea pigs failed to develop any cutaneous changes after inoculation with either dead spores or mycelia. In contrast, guinea pigs that had recovered from a T. mentagrophytes infection reacted to topically applied spores by producing pustules but failed to develop pustules either grossly or microscopically when inoculated with mycelia. Because differences in the activation of C' and the subsequent generation of the polymorphonuclear leukocyte (PMN) chemoattractant, C5a, might account for our in vivo findings, we measured the amount of C5a activated in vitro when serum was incubated with equivalent amounts of spores or mycelia. Spores consistently activated more C' to C5a than mycelia, although each could activate serum C'. The results support previous studies that show a direct correlation between the clinical manifestations of a dermatophytic infection and the development of immunity against the dermatophyte. Furthermore, the data suggest that a dermatophyte's predominant morphology during an infection may play a critical role in producing pustules by activating C' and chemoattracting PMNs into the fungus-laden stratum corneum.

Animals↗
PubMed1985

Establishment of basal cell carcinoma in culture: evidence for a basal cell carcinoma-derived factor(s) which stimulates fibroblasts to proliferate and release collagenase.

The connective tissue adjacent to basal cell carcinomas (BCC) is frequently abnormal and contains increased numbers of fibroblasts and increased extractable collagenase. To determine whether BCC could produce these alterations by releasing mediators that regulated fibroblast function, we established BCC in culture and tested the ability of their culture supernatants to alter fibroblast proliferation and production of collagenase. Using tissue culture plates coated with type IV collagen and containing x-irradiated 3T3 feeder cells, we established epithelial colonies from 47% of the BCC cultured. The BCC-derived colonies differed from normal epidermal cell colonies in their morphology, growth rate, and keratin production. Culture supernatants from 4 out of 5 confluent BCC-derived colonies contained factors that stimulated fibroblasts to proliferate and release collagenase. These findings show that BCC-derived epidermal cell colonies release mediators which alter fibroblast functions and suggest that some of the connective tissue changes associated with BCC in vivo are the result of BCC-fibroblast interactions.

Aged↗
PubMed1983

Gram-negative bacterial toe web infection: successful treatment with a new third generation cephalosporin.

Fifteen patients with gram-negative bacterial toe web infections were treated for 1 week with intramuscular cefoperazone, a broad-spectrum third generation cephalosporin. Initial bacterial cultures in eleven patients (73%) grew more than one gram-negative organism. Pseudomonas aeruginosa was the most frequent isolate. All bacteria isolated were sensitive to cefoperazone (Cefobid). Swelling, redness, and flow of exudate resolved within 1 week of antibiotic administration. By day 7 there was no evidence of inflammation, and denuded areas had begun to re-epithelialize. Side effects were mild and did not require cessation of therapy. This antibiotic causes rapid resolution of a disease which previously required prolonged hospitalizations.

Adult↗
PubMed1983

Collagen-induced arthritis in rats: antigen-specific suppression of arthritis and immunity by intravenously injected native type II collagen.

Collagen-induced arthritis (CIA) developed in 70 to 90% of rats immunized with heterologous type II collagen. CIA was reduced to 0 to 18% when rats were injected i.v., i.e., pretreated, with 1 mg of soluble native type II collagen before immunization. Concomitant with the suppression of CIA were significant suppression of IgM, IgG, and delayed-type hypersensitivity (DTH) responses to type II collagen. Suppression of CIA and immunity to collagen was antigen-specific, related to dose and route of administration, and occurred only when 1 mg of collagen was injected i.v. either 32, 7, or 4 days before, or 7 days after immunization. Once CIA was established, however, neither arthritis nor immunity could be suppressed. To determine if adjuvant-induced arthritis (AIA), like CIA, could be suppressed by i.v. pretreatment with type II collagen, rats were given 1 mg of type II collagen or PBS i.v. before injection with mycobacteria and oil. AIA was not suppressed, and arthritis appeared in both groups at a similar incidence and severity. Sera from 26 rats with severe AIA that was collected between days 14 and 35 after injection were assayed for IgG to homologous rat type II collagen and were found to be negative. These findings further support the hypothesis that CIA in rats is mediated by immunity to type II collagen and also suggest that CIA and AIA have different primary pathogenic mechanisms.

Animals↗