Biomedical subjects

R N Johnson

Publications and source records attributed to R N Johnson.

186 records · Page 11Linked to original sources

PubMedDate not supplied

A new focus of kala-azar due to Leishmania donovani sensu lato in Kenya.

Three Masai children from Kekonyokie South Location, Kajiado District were diagnosed with visceral leishmaniasis (kala-azar). Leishmanial isolates from the patients were characterized as Leishmania donovani sensu lato, by cellulose acetate electrophoresis. Case histories indicated that the disease was acquired locally. A survey of 409 children at 7 local primary schools and one nursery school revealed no additional case. Sandfly surveys using light traps and sticky paper traps recovered 10 species of sandfly, including 2 Phlebotomus species. P. martini was prevalent throughout the area. P. orientalis was only rarely encountered, but it was the first collection record of this species in the southern portion of the Rift Valley in Kenya. Although no Leishmania-infected sandfly was found, P. martini is probably the vector of kala-azar in the location, as it is elsewhere in Kenya.

Adolescent↗

PubMedDate not supplied

Genetic control of the honey bee (Apis mellifera) dance language: segregating dance forms in a backcrossed colony.

We studied the genetic control of the dance dialects that exist in the different subspecies of honey bees (Apis mellifera) by observing the variation in dance form observed in a backcross between two lines that showed widely different dance dialects. To do this we generated the reciprocal of the cross performed by Rinderer and Beaman (1995), thus producing phenotypic segregation of dance forms within a single colony rather than between colonies. Our results are consistent with Rinderer and Beaman (1995) in that inheritance of the transition point from round dancing --> waggle dancing is consistent with control by a single locus with more than one allele. That is, we found one dance type to be dominant in the F(1), and observed a 1:1 segregation of dance in a backcross involving the F(1) and the recessive parent. However, we found some minor differences in dance dialect inheritance, with the most significant being an apparent reversal of dominance between our cross (for us "black" is the dominant dialect) and that of Rinderer and Beaman (1995) (they report "yellow" to be the dominant dialect). We also found that our black bees do not perform a distinct sickle dance, whereas the black bees used by Rinderer and Beaman (1995) did perform such a dance. However, our difference in dominance need not contradict the results of Rinderer and Beaman (1995), as there is no evidence that body color and dominance for dance dialect are linked.

Animal Communication↗

PubMedDate not supplied

Observations on the effect of morphine on thalamocortical excitability in the cat.

The acute effects of morphine on the thalamocortical augmenting response in the cat were evaluated. The thalamocortical augmenting response was elicited by delivering pairs of pulses to the ventrolateral thalamus and recording from ipsilateral sensorimotor cortex. A biphasic, dose-related, naloxone-attenuable effect on the augmenting response elicited by pulse pairs was observed. Although the clinical significance of those morphine-induced changes is currently uncertain, they can be correlated with the convulsant and anticonvulsant effects of different doses of morphine.

Animals↗

PubMedDate not supplied

Kearns-Sayre syndrome: a case report and review.

In 1958, Kearns and Sayre described a multisystem entity, now known as Kearns-Sayre syndrome (KSS). The syndrome is defined as exhibiting a triad of thus far unexplained degenerative conditions: progressive external ophthalmoplegia, retinal pigmentary degeneration, and heart block. Commonly accompanying findings include cerebellar dysfunction and CSF protein levels above 100 mg/dl. Symptoms usually appear in early childhood, but the onset has been seen occasionally in young adults. KSS is a mitochondrial disorder that occurs rarely; the actual incidence is unknown. Ocular findings consist of bilateral ptosis, chronic progressive external ophthalmoplegia, and pigmentary retinopathy. Corneal clouding and optic neuritis are infrequent. We herein report a classic case of Kearns Sayre syndrome and discuss the findings.

Adult↗

PubMedDate not supplied

Surgical results for proliferative vitreoretinopathy.

We reviewed 88 consecutive eyes that underwent vitrectomy for retinal detachment with proliferative vitreoretinopathy (PVR) and were followed a minimum of six months. A primary goal of the surgery was the meticulous trimming of the vitreous base in hopes of decreasing the incidence of post-operative reproliferation and anterior PVR. Those eyes with anterior PVR had aggressive release of vitreous base contraction (anteroposterior and circumferential) with intraocular scissors. All posterior tractional membranes were removed. All eyes received long-acting gas for postoperative retinal tamponade. Macular reattachment was achieved in 78 (88.6%) eyes. Forty-six (52.3%) obtained at least 5/200 vision. Seventeen (19%) eyes were re-operated at least once. We compared the importance of initial lens status (pseudophakic, aphakic, phakic), need for relaxing retinotomy, presence of anterior PVR, and history of previous vitrectomy on the anatomic and visual results. No single factor was responsible for a statistically significant effect on either vision or anatomic success, except for the need for a relaxing retinotomy, which carried with it a decreased chance of an eye obtaining 5/200 vision (Fisher's exact test, p = 0.03).

Adolescent↗

PubMedDate not supplied

Central serous chorioretinopathy in two families.

PURPOSE AND METHODS: The reported occurrence of central serous chorioretinopathy (CSCR) in families is rare. We report two families (five patients) who have been diagnosed with CSCR. The diagnosis of CSCR was made on clinical and fluorescein angiographic findings. RESULTS: Three members of the first family and two members of the second family had CSCR. Affected individuals were all males. CONCLUSIONS: CSCR has been associated with psychological and emotional stress and the occurrence of CSCR in families may be due to similar inherited psychological and physiological characteristics and responses that predispose these families to the development of CSCR.

Adult↗