Biomedical subjects

J Landsberg

Publications and source records attributed to J Landsberg.

6 recordsLinked to original sources

PubMed2001

Classification and identification of Pfiesteria and Pfiesteria-like species.

Dinoflagellates can be classified both botanically and zoologically; however, they are typically put in the botanical division Pyrrhophyta. As a group they appear most related to the protistan ciliates and apicomplexans at the ultrastructure level. Within the Pyrrhophyta are both unarmored and armored forms of the dominant, motile flagellated stage. Unarmored dinoflagellates do not have thecal or wall plates arranged in specific series, whereas armored species have plates that vary in thickness but are specific in number and arrangement. In armored dinoflagellates, the plate pattern and tabulation is a diagnostic character at the family, subfamily, and even genus levels. In most cases, the molecular characterization of dinoflagellates confirms the taxonomy on the basis of external morphology; this has been demonstrated for several groups. Together, both genetic and morphological criteria are becoming increasingly important for the characterization, separation, and identification of dinoflagellates species. Pfiesteria and Pfiesteria-like species are thinly armored forms with motile dinospore stages characterized by their distinct plate formulae. Pfiesteria piscicida is the best-known member of the genus; however, there is at least one other species. Other genetically and morphologically related genera, now grouped under the common names of "Lucy," "Shepherd's crook," and cryptoperidiniopsoid, are being studied and described in separate works. All these other heterotrophic dinoflagellate groups, many of which are thought to be benign, co-occur in estuarine waters where Pfiesteria has been found.

Animals↗

PubMed1995

Analysis of copper and lead in hair using the nuclear microscope; results from normal subjects, and patients with Wilson's disease and lead poisoning.

We have recently developed a technique utilizing the nuclear microscope to analyse accurately the trace element content of hair at concentrations of ppm and to differentiate between the levels within hair and those due to surface contamination. Hair was analysed from four patients with Wilson's disease (systemic copper overload), one patient with sub-acute lead poisoning, and three control subjects, and the concentrations and distributions of lead and copper across the hair shafts were shown. However, there was no increase in the copper content of hair from patients with Wilson's disease compared with those of normal subjects, indicating that the high copper levels of many tissues in this disease are not reflected in hair. In contrast, hair samples from the patient with lead poisoning showed maximum concentrations of 14 (+/-2) micrograms g-1, compared with normal levels of less than 1 micrograms g-1. Further, the composition of the hairs along the shaft reflected the temporal changes of lead levels in the patient during lead elimination.

Adolescent↗

PubMed1987

Cryosurgical depigmentation of the gingiva. A case report.

Gingival melanin pigmentation (GMP) occurs in all races of man. Although clinical melanin pigmentation does not present a medical problem, demand for cosmetic therapy is commonly made by fair-skinned people with moderate GMP. The present study was undertaken to test the effectiveness of cryosurgical destruction of the gingival epithelium in the removal of gingival melanin pigmentation. The patient was a fair-skinned Ashkenazi Jew with moderate GMP who demanded any possible "cosmetic therapy" which would convert her "black gums" to "normal". Gingival cryosurgery was carried out by segments. A gas expansion cryoprobe cooled to -81 degrees C was applied to the gingiva for 10 s. Frozen sites thawed spontaneously within 1 min. Superficial necrosis became apparent within a week. Treated sites were covered by epithelium within 2 weeks following freezing and keratinization was completed after 3-4 weeks. The treated gingiva appeared normal and remained depigmented until the present time, 20 months following freezing. It is concluded that cryosurgery may prove to be the treatment of choice when gingival depigmentation is indicated.

Adult↗

PubMed1984

The toothbrush and gingival traumatic injury.

This paper explores, by means of clinical observation, toothbrush misuse and its relationship to gingival recession/clefting. The morphology of the lesions created is correlated with the vigor, duration, frequency and direction of the toothbrush abuse. In addition, histologic observations of biopsied tissue from different types of clefts and recessions are used as a basis for discussion of the possible pathogenesis of this type of lesion.

Adolescent↗

PubMedDate not supplied

Etiologies, observations and reporting of estuarine finfish lesions.

Lesions in estuarine finfish are associated with a variety of organisms including parasites and bacterial, viral, and fungal infectious agents. In addition, trauma, suboptimal water quality, and other abiotic stress factors may result in the loss of homeostasis. We have observed solitary ulcerative lesions on menhaden sampled from the Chesapeake Bay, Maryland, the Pimlico River, North Carolina, and the St. Johns River, Florida. Histologically, the lesions demonstrated a marked chronic inflammatory infiltrate and granulomas in response to fungal hyphae throughout large areas of exposed necrotic muscle. Gram-negative rod-shaped bacteria were also observed in the lesions, a common finding in ulcers of aquatic organisms. Similar observations in menhaden and other species have been described previously in the literature as ulcerative mycosis, mycotic granulomatosis, red spot disease, and epizootic ulcerative syndrome. Despite the many different known causes of fish lesions, the popular press and the scientific literature have recently emphasized Pfiesteria piscicida and other Pfiesteria-like dinoflagellates (and their bioactive compounds) as the primary causative agent for finfish lesions, particularly mycotic granulomatous ulcers in Atlantic menhaden. While some laboratory data suggest that Pfiesteria may play a role in field-observed lesions, much more cause-and-effect evidence is needed to determine the importance of other risk factors, both alone or and in combination with Pfiesteria. In order to better understand the etiology of lesion initiation and progression in estuarine finfish, accurate assessments of environmental conditions collected on appropriate temporal and spatial scales, and fish morphological indicators consistent with gross and histological pathologic terminology, should be used for reporting fish lesion observations and kills. Further, this outlook will help to avoid bias and may foster a broader perspective for examining the health of estuarine systems in general.

Animals↗

PubMedDate not supplied

Microanalysis of senile plaques using nuclear microscopy.

Silver-staining "senile" plaques occurring in the brain are a major part of the pathology of Alzheimer's disease. The elemental composition of these structures, and the possible presence of aluminum and silicon in these structures, has been the subject of an increasing research effort over the last decade. However, the results have often been contradictory. Using a scanning proton microprobe, the elemental composition of senile plaques has been determined. This instrument, similar to an electron probe, uses a focused beam of protons scanned across a sample to map the elements. The technique is absolutely quantitative and is sensitive down to the parts per million level. Tissue from six cases of clinically and pathologically characterized cases of Alzheimer's disease and two aged neurologically normal controls was scanned. It was found that aluminum and silicon occur at a level of 50 ppm or greater in the cores of 20% of senile plaques and that the total occurrence of aluminum or silicon in scans containing plaques was not above background. The major uncertainties affecting interpretation of results of this kind are discussed, and it is suggested that the least controllable factor is contamination in the reagents used to prepare and stain the tissue. This indicates that until plaques can be unambiguously identified and analyzed in untreated tissue, no conclusion can be reached on whether senile plaques contain aluminum and silicon.

Aged↗