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Biomedical subjects

P Ma

Publications and source records attributed to P Ma.

At least 73 records · Page 4Linked to original sources
PubMed1989

Mutations in signal sequence cleavage domain of preproparathyroid hormone alter protein translocation, signal sequence cleavage, and membrane-binding properties.

Signal sequences, known to mediate the targeting of nascent secreted proteins to membranes, share common structural domains: a positively charged amino-terminus, a hydrophobic core, and a signal cleavage domain. Mutations have been introduced into the cDNA encoding the signal sequence of the mammalian protein preproparathyroid hormone to analyze the roles played by the signal cleavage domain in secretion. Two mutant genes were constructed missing the entire six-residue propeptide sequence and several residues of the signal cleavage domain. The effects of these mutations on signal function were assessed after expression in clonal cell lines and in a transcription-linked translation system. Alterations in the signal cleavage domain resulted in reduced translocation and signal cleavage. Furthermore, in one mutant, the removal of the signal cleavage domain converted the signal into a membrane anchor sequence. The nonhydrophobic sequences at the end of the signal sequence thus crucially affect the translocation, cleavage, and membrane-binding properties of signal sequences.

Amino Acid Sequence↗
PubMed1989

[Detection of HIV antibody and antigen].

A total of 75 specimens (45 sera, 17 CSF and 13 stool) was collected from 65 participants (39 AIDS, 14 high risk group and 12 laboratory personnel) and HIV antibody and antigen were detected. Twenty sera and 16 CSF submitted by AIDS patients showed positive antibody reactions in both ELISA and Western blot assay, whereas, antibody was not detected in the sera and the CSF obtained from high risk group or laboratory personnel. An overall of 21% (10/48) positive rate was found in the specimens submitted by AIDS patients for HIV antigen detection by ELISA. The positive rates of HIV antigen in sera, CSF and stool specimen from the AIDS patients were 30% (6/20), 13% (2/16) and 17% (2/12), respectively.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Cryptosporidiosis. Traveler's diarrhea in two families.

Intestinal cryptosporidiosis was diagnosed in three infants (aged 6 to 21 months), one child (aged 3 years), and two adult members of two families after their return from travel to the African continent. Examination of stools from all patients revealed acid-fast cryptosporidial oocysts on direct fecal smears stained by the modified cold Kinyoun technique. Five of the six were symptomatic with watery diarrhea, anorexia, and abdominal pain. Elevated anticryptosporidial titers were detected in five patients, two of whom were asymptomatic. Cryptosporidiosis should be included in the differential diagnosis of traveler's diarrhea.

Adult↗
PubMed1985

The diagnostic value of a ring infiltrate in acanthamoebic keratitis.

During the past ten years it has become increasingly apparent that acanthamoebae can directly infect the cornea, usually after trauma, associated with contaminated water or soft contact lens wear. Thirteen cases of acanthamoebic keratitis have been published. In only three of these cases was the diagnosis first made by microbiologic methods, while in the others it was made only after pathologic examination of resected corneal specimens or enucleated eyes. We report three additional cases, two of which were accurately diagnosed by corneal scrape-smears and cultures before penetrating keratoplasty was performed. The reason for the accurate laboratory diagnosis in these cases was the presence of a diagnostic paracentral annular corneal infiltrate or abscess, a feature identified in over two-thirds of the earlier cases but one which has not been adequately emphasized or pursued for its early diagnostic value. We review the other clinical and epidemiological features of this entity, microbiological diagnostic techniques, the pathologic aspects, the role of topically and systemically administered medicaments, and finally point out the almost unavoidable role of penetrating keratoplasty after the temporizing effects of medical treatments have been achieved.

Adult↗
PubMed1985

Characterization and evolution of a single-copy sequence from the human Y chromosome.

To study the evolution and organization of DNA from the human Y chromosome, we constructed a recombinant library of human Y DNA by using a somatic cell hybrid in which the only cytologically detectable human chromosome is the Y. One recombinant (4B2) contained a 3.3-kilobase EcoRI single-copy fragment which was localized to the proximal portion of the Y long arm. Sequences homologous to this human DNA are present in male gorilla, chimpanzee, and orangutan DNAs but not in female ape DNAs. Under stringent hybridization conditions, the homologous sequence is either a single-copy or a low-order repeat in humans and in the apes. With relaxed hybridization conditions, this human Y probe detected several homologous DNA fragments which are all derived from the Y in that they occur in male DNAs from humans and the apes but not in female DNAs. In contrast, this probe hybridized to highly repeated sequences in both male and female DNAs from old world monkeys. Thus, sequences homologous to this probe underwent a change in copy number and chromosomal distribution during primate evolution.

Adult↗
PubMed1984

Respiratory cryptosporidiosis in the acquired immune deficiency syndrome. Use of modified cold Kinyoun and Hemacolor stains for rapid diagnoses.

We report three cases of primary intestinal cryptosporidiosis with bilateral interstitial pneumonia. The diagnoses were made using two rapid (one-minute) staining procedures, modified cold Kinyoun's solution and a Hemacolor set, on touch preparations of lung biopsy material, sputum, and stool. Intracellular cryptosporidia oocysts in alveolar macrophages suggest possible hematogenous spread of this agent. Opportunistic cryptosporidiosis should be included in the differential diagnosis of pneumonia in patients with acquired immune deficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Cryptosporidiosis in homosexual men.

Between April 1982 and June 1983, cryptosporidiosis was diagnosed in six homosexual men. Four patients with the acquired immunodeficiency syndrome had lymphopenia, cutaneous anergy, and profoundly impaired cellular immunity; their cryptosporidiosis was severe, unremitting, and refractory to all therapy. Two patients without other opportunistic infections or Kaposi's sarcoma had moderately impaired cellular immunity but not lymphopenia or anergy; their enteric illness was self-limited. Cryptosporidium recently had been recognized as a human pathogen that is transmitted through fecal-oral contamination. The severity of human cryptosporidiosis appears to be determined primarily by immunocompetence of the patient. These six homosexual men, with different degrees of immunologic impairment, had two clinically divergent forms of cryptosporidiosis. Their cases raise questions about human transmission of Cryptosporidium and the prognostic significance of this disease in patients who are at high risk for developing the acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Three-step stool examination for cryptosporidiosis in 10 homosexual men with protracted watery diarrhea.

Cryptosporidiosis, a zoonosis caused by Cryptosporidium species, is a newly recognized coccidial protozoan infection causing severe protracted watery diarrhea in humans. In August 1981, the first case of cryptosporidiosis in a homosexual man with acquired immune deficiency syndrome (AIDS) was reported; diagnosis was determined by intestinal biopsy. It is necessary to adopt a simple laboratory diagnostic procedure to screen large numbers of suspected cases. A three-step stool examination was developed to demonstrate Cryptosporidium oocysts and the diagnostic and infective stages of the infection in 10 homosexual men with AIDS. This is a less invasive, less costly, and more sensitive test than intestinal biopsy and has been designed to prevent confusion caused by yeast cells that are frequently present in stool, leading to a false diagnosis. The examination consists of preliminary differential determination by iodine wet mount, definitive identification by modified Kinyoun acid-fast staining, and a more effective method of concentrating oocysts, by Sheather's sugar cover-slip flotation method.

Acquired Immunodeficiency Syndrome↗
PubMed1981

A case of keratitis due to Acanthamoeba in New York, New York, and features of 10 cases.

A man in New York, New York, contracted keratitis caused by Acanthamoeba castellanii. The diagnosis was delayed because amoebae were not initially suspected as the infectious organism. The culture isolate and the amoebae in corneal sections were identified as A. castellanii by immunofluorescence using antiserum to plasma membranes of this species. With the rapid agar disk diffusion method, the amoebae were shown to e susceptible to pimaricin (0.5%) and resistant to greater than 1,000-micrograms/ml levels of paromomycin, polymyxin B-bacitracin-neomycin, acriflavine, 5-fluorocytosine, amphotericin B, gentamicin, and trimethoprim-sulfamethoxazole. The infection responded to treatment with pimaricin administered with several other drugs. This infection is the eighth case reported in the literature of acanthamoebic keratitis and emphasizes the need for clinicians to consider acanthamoebic infection in the differential diagnosis of eye infections that fail to respond to bacterial, fungal, and viral therapy.

Adult↗
PubMed1980

A sudden decline in ampicillin resistance in Salmonella typhimurium.

Starting in 1975, an abrupt decline in ampicillin resistance of Salmonella typhimurium (the most common and antibiotic-resistant serotype) occurred in New York City. The present lower rate of 5% to 7.9% at our hospitals represents a return to the 1965 level. At the same time, the ampicillin resistance in S typhimurium from calves and other farm animals from upper New York State, which has been rising since 1972, has reached 75%. Substantial differences between levels of resistance in Escherichia coli from animals and humans were also noted. The divergence of the trends in S typhimurium from these two sources in New York State suggests a substantial degree of separation of the respective reservoirs of Salmonella and of antibiotic resistance.

Ampicillin↗