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Biomedical subjects

N Komar

Publications and source records attributed to N Komar.

28 records · Page 2Linked to original sources
PubMed1980

Hyperaldosteronism, hyperparathyroidism, medullary sponge kidneys, and hypertension.

Hyperparathyroidism and hyperaldosteronism coexisted in association with medullary sponge kidneys in a 27-year-old woman with severe hypertension. A modest fall in systolic and diastolic pressure followed removal of a parathyroid adenoma. Blood pressure was controlled with spironolactone therapy and restored to normal after removal of an aldosterone-secreting adrenal tumor. Elevated levels of aldosterone may have been responsible for the severe hypertension, while hypercalcemia may have had a synergistic effect on the arteriolar response to circulating vasoactive peptides.

Adenoma↗
PubMed1979

Calculation of evolutionary trees from sequence data.

Evolutionary trees are usually calculated from comparisons of protein or nucleic acid sequences from present-day organisms by use of algorithms that use only the difference matrix, where the difference matrix is constructed from the sequence differences between pairs of sequences from the organisms. The difference matrix alone cannot define uniquely the correct position of the ancestor of the present-day organisms (root of the tree). Furthermore, methods using the difference matrix alone often fail to give the correct pattern of tree branching (topology) when the different sequences evolve at different rates. Only for equal rates of evolution can the difference matrix (when used with the so-called matrix method) yield exactly the correct topology and root. In this paper we present a method for calculating evolutionary trees from sequence data that uses, along with the difference matrix, the rate of evolution of the various sequences from their common ancestor. It is proven analytically that this method uniquely determines both the correct topology and root in theory for unequal rates of sequence evolution. How one would estimate an ancestral sequence to be used in the method is discussed in particular for the 5S RNA sequences from prokaryotes and eukaryotes and for ferredoxin sequences.

Amino Acid Sequence↗
PubMedDate not supplied

Competence of American robins as reservoir hosts for Lyme disease spirochetes.

To explore the competence of American robins as a reservoir for Lyme disease spirochetes, we determined the susceptibility of these birds to tickborne spirochetes and their subsequent infectivity for larval vector ticks. Robins acquired infection and became infectious to almost all xenodiagnostic ticks soon after exposure to infected nymphal ticks. Although infectivity waned after 2 months, the robins remained susceptible to reinfection, became infectious again, and permitted repeated feeding by vector ticks. In addition, spirochetes passaged through birds retained infectivity for mammalian hosts. American robins become as infectious for vector ticks as do reservoir mice, but infectivity in robins wanes more rapidly.

Animals↗
PubMedDate not supplied

Crow deaths as a sentinel surveillance system for West Nile virus in the northeastern United States, 1999.

In addition to human encephalitis and meningitis cases, the West Nile (WN) virus outbreak in the summer and fall of 1999 in New York State resulted in bird deaths in New York, New Jersey, and Connecticut. From August to December 1999, 295 dead birds were laboratory-confirmed with WN virus infection; 262 (89%) were American Crows (Corvus brachyrhynchos). The New York State Department of Health received reports of 17,339 dead birds, including 5,697 (33%) crows; in Connecticut 1,040 dead crows were reported. Bird deaths were critical in identifying WN virus as the cause of the human outbreak and defining its geographic and temporal limits. If established before a WN virus outbreak, a surveillance system based on bird deaths may provide a sensitive method of detecting WN virus.

Animals↗
PubMedDate not supplied

Serologic evidence for West Nile virus infection in birds in the New York City vicinity during an outbreak in 1999.

As part of an investigation of an encephalitis outbreak in New York City, we sampled 430 birds, representing 18 species in four orders, during September 13-23, 1999, in Queens and surrounding counties. Overall, 33% were positive for West Nile (WN) virus-neutralizing antibodies, and 0.5% were positive for St. Louis encephalitis virus-neutralizing antibodies. By county, Queens had the most seropositive birds for WN virus (50%); species with the greatest seropositivity for WN virus (sample sizes were at least six) were Domestic Goose, Domestic Chicken, House Sparrow, Canada Goose, and Rock Dove. One sampled bird, a captive adult Domestic Goose, showed signs of illness; WN virus infection was confirmed. Our results support the concept that chickens and House Sparrows are good arbovirus sentinels. This study also implicates the House Sparrow as an important vertebrate reservoir host.

Animals↗
PubMedDate not supplied

Experimental infection of chickens as candidate sentinels for West Nile virus.

We evaluated the susceptibility, duration and intensity of viremia, and serologic responses of chickens to West Nile (WN) virus (WNV-NY99) infection by needle, mosquito, or oral inoculation. None of 21 infected chickens developed clinical disease, and all these developed neutralizing antibodies. Although viremias were detectable in all but one chicken, the magnitude (mean peak viremia <10,000 PFU/mL) was deemed insufficient to infect vector mosquitoes. WNV-NY99 was detected in cloacal and/or throat swabs from 13 of these chickens, and direct transmission of WNV-NY99 between chickens occurred once (in 16 trials), from a needle-inoculated bird. Nine chickens that ingested WNV-NY99 failed to become infected. The domestic chickens in this study were susceptible to WN virus infection, developed detectable antibodies, survived infection, and with one exception failed to infect cage mates. These are all considered positive attributes of a sentinel species for WN virus surveillance programs.

Animals↗
PubMedDate not supplied

Exposure of domestic mammals to West Nile virus during an outbreak of human encephalitis, New York City, 1999.

We evaluated West Nile (WN) virus seroprevalence in healthy horses, dogs, and cats in New York City after an outbreak of human WN virus encephalitis in 1999. Two (3%) of 73 horses, 10 (5%) of 189 dogs, and none of 12 cats tested positive for WN virus-neutralizing antibodies. Domestic mammals should be evaluated as sentinels for local WN virus activity and predictors of the infection in humans.

Animals↗
PubMedDate not supplied

West Nile virus outbreak among horses in New York State, 1999 and 2000.

West Nile (WN) virus was identified in the Western Hemisphere in 1999. Along with human encephalitis cases, 20 equine cases of WN virus were detected in 1999 and 23 equine cases in 2000 in New York. During both years, the equine cases occurred after human cases in New York had been identified.

Aedes↗
PubMedDate not supplied

Comparative West Nile virus detection in organs of naturally infected American Crows (Corvus brachyrhynchos).

Widespread deaths of American Crows (Corvus brachyrhynchos)were associated with the 1999 outbreak of West Nile (WN) virus in the New York City region. We compared six organs from 20 crow carcasses as targets for WN virus detection. Half the carcasses had at least one positive test result for WN virus infection. The brain was the most sensitive test organ; it was the only positive organ for three of the positive crows. The sensitivity of crow organs as targets for WN virus detection makes crow death useful for WN virus surveillance.

Bird Diseases↗