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R Beach

Publications and source records attributed to R Beach.

35 records · Page 2Linked to original sources
PubMed1985

Rapid enzymological identification of leishmanial isolates in Kenya.

Leishmanial isolates from Kenya were identified as being either Leishmania major, L. donovani or L. aethiopica by using cellulose acetate electrophoresis. Species determination is based on the electrophoretic pattern for glucose phosphate isomerase alone. This report describes the technique and presents data on its reliability as a rapid identification test for Leishmania isolates from the same geographical region.

Electrophoresis, Cellulose Acetate↗
PubMed1985

Modification of sand fly biting behavior by Leishmania leads to increased parasite transmission.

To attempt rodent-sand fly-rodent transmission of Leishmania major, laboratory-reared Phlebotomus doboscqi were fed on L. major-infected mice and then refed on uninfected mice 21 days later. Flies which refed either probed 1-2 times and took a full blood meal in less than 10 min or probed 3 or more times and took little or no blood during a period of 15 min or more. When dissected, 7 of 8 flies which experienced difficulty in obtaining a blood meal had flagellates in their cibaria, an observation supporting the hypothesis that parasites in this part of the alimentary canal modify normal blood feeding behavior. None of the infected females which probed 1-2 times had similar anterior station infections. Infected sand flies transmitted L. major to uninfected mice and a single fly, transferred from 1 mouse to the next while repeatedly attempting to take blood, infected 5 mice. During a year-long survey in Baringo District, Kenya, we collected 9,182 female sand flies. Only 2 of the 278 P. duboscqi captured during this collection were infected with L. major; however, 18 of the 789 small rodents from this area were infected with L. major. Parasite interference with normal blood feeding may explain how a relatively small population of P. duboscqi, only a few of which are infected with L. major, can amplify parasite transmission thereby maintaining a disproportionately large reservoir in local rodents.

Animals↗
PubMed1984

Regulation of mitotic activity and the cell cycle in primary chick muscle cells by neurotransferrin.

We previously demonstrated that neurotransferrin (NTF), a transferrin extracted from adult chicken peripheral nerves, promotes growth of primary chick muscle cells in the absence of embryo extract. NTF was shown to stimulate DNA synthesis and cell proliferation. In the present study, we demonstrate that NTF is a mitogen using two independent methods; counts of orcein-stained mitotic figures and analysis of cell cycle kinetics with a fluorescence-activated cell sorter. In low-density cultures mitotic activity increases with increasing doses of NTF followed by a plateau at concentrations greater than 6 micrograms/ml. Residual, embryonic mitotic activity progressively declines with time after plating muscle cells in the absence of NTF. Absence of NTF for 2 days causes cells to lose irreversibly their myogenic potential. In the presence of NTF, mitotic activity increases for 2 days followed by a decline concurrent with myoblast fusion and formation of myotubes. Cell cycle analysis showed that NTF addition causes cell populations to shift from G1 to S and G2 + M within 18.5 hr. Muscle cells, plated at high densities in the absence of NTF, show mitotic activities similar to those plated at low densities in the presence of NTF. Addition of NTF to high-density cultures is ineffective in stimulating mitosis. These studies show that at typical cell plating densities, NTF is a required mitogen for primary chick muscle cell cultures.

Animals↗
PubMed1984

Cutaneous leishmaniasis in Kenya: transmission of Leishmania major to man by the bite of a naturally infected Phlebotomus duboscqi.

One leishmanial stock was isolated from a Phlebotomus duboscqi female captured in Baringo District, Kenya, and others from papular lesions that developed at sites where this sandfly had fed on a man. When characterized by cellulose acetate electrophoresis (eight enzymes examined), these isolates proved to be identical to known Leishmania major strains from man and a rodent (Arvicanthis sp.) and different from L. donovani and L. adleri, which also occur in Baringo. This is the first case of human cutaneous leishmaniasis caused by L. major reported from Kenya.

Electrophoresis, Cellulose Acetate↗
PubMed1984

Production of human chorionic gonadotrophin by a hepatoblastoma resulting in precocious puberty.

A two year old boy presented with precocious puberty associated with hepatoblastoma. Serum concentrations of beta human chorionic gonadotrophin and alpha-fetoprotein were raised. An aggressive chemotherapeutic regimen resulted in useful palliation and interesting changes in the beta human chorionic gonadotrophin and alpha-fetoprotein concentrations. In contrast to a previous report, the ultrastructure of the tumour showed frequent Golgi apparatus but no other electron dense membrane bound vesicles.

Carcinoma, Hepatocellular↗
PubMed1979

Congenital complete heart block in the newborn associated with maternal systemic lupus erythematosus and other connective tissue disorders.

Four babies with complete heart block associated with maternal systemic lupus erythematosus (SLE) are described, together with a 5th baby whose mother had serological abnormalities only. One baby had a rapidly fatal outcome, one has required digoxin for heart failure, and the remaining 3 are asymptomatic but remain in complete heart block. Additional manifestations were present in 2 of them. The spectrum of neonatal abnormalities that may occur in association with maternal SLE and related connective tissue disorders is discussed, together with the possible causes and the prognosis. We conclude that congenital heart block is more common than had previously been appreciated.

Adult↗
PubMedDate not supplied

Spectrum of genital human papillomavirus infection in a female adolescent population.

BACKGROUND: Human papillomavirus infection is a sexually transmitted disease associated with cervical dysplasia and carcinoma. GOAL OF THIS STUDY: To determine prevalence rates of cervical human papillomavirus infection compared with other sexually transmitted diseases and risk factors associated with human papillomavirus infection among adolescent women, we evaluated 634 patients attending three urban adolescent clinics. STUDY DESIGN: Patient evaluation included Pap smears; screening for chlamydia, gonorrhea, and trichomoniasis; and testing of cervical swab samples for human papillomavirus DNA. RESULTS: Cervical human papillomavirus was the most common STD in our population (15.6%), followed by infection with Chlamydia trachomatis (11.0%), Neisseria gonorrhoeae (7.1%), and Trichomonas vaginalis (5.4%). The most prevalent human papillomavirus types were 16/18 (7.3%), followed by 31/33/35 (4.7%) and 6/11 (3.5%). When genital warts on exam, low-grade squamous intraepithelial lesions on cytology, or cervical human papillomavirus DNA were considered as indicators of genital human papillomavirus infection, 24% of patients had any manifestation of infection, including 15% with clinically apparent infection (genital warts), 36% with cytologically apparent infection without warts, and 49% with subclinical infection only (cervical human papillomavirus DNA without low-grade squamous intraepithelial lesions or warts). Factors associated with detection of cervical human papillomavirus DNA by multivariate analysis included number of lifetime sexual partners and genital warts on exam. CONCLUSION: Cervical human papillomavirus infection was the most prevalent sexually transmitted disease among an ethnically diverse group of urban adolescent females, with a large proportion of infections neither clinically nor cytologically apparent. The strong association with lifetime sexual partners substantiates that cervical human papillomavirus is acquired predominantly by sexual contact and often soon after the onset of sexual activity.

Adolescent↗
PubMedDate not supplied

Analysis of contributing factors to the occurrence of off-focus radiation (OFR).

Off-focus radiation (OFR) has previously been described by many investigators [R. Thoraeus, Acta Radiologica 18, 753 (1937); L. Mallet and R. Maurin, Radiology 48, 628-632 (1947); J. F. Timmer, Medicamundi 19(2), 52-54 (1974); G. U. Rao, Appl. Radiol. 3(3), 45-49 (1974); R. Birch, Br. J. Radiol. 49, 951-955 (1976); W. W. Roeck, AAPM Symposium, 217-247 (1991)]. Off-focus radiation is frequently manifested on radiographs by the appearance of faint images of anatomical structures outside the collimated field of interest, i.e., soft tissues, ear lobes and hair, which we will refer to as "penumbral images." The observable small detail resolution within these penumbral images led to the assumption that minute sources of increased radiation intensity (secondary microfocal spots) must be present outside the area of the primary focal spot. The existence of these multiple secondary microfocal spots has been established and their locations within the area of the anode surface from which the general OFR originates was identified. The number, size, and distribution of the secondary focal spots vary over time and their magnitudes vary widely. The source of the well-focused electron beams creating the spots is attributed to the cold cathode emission principle.

Humans↗