A gene for dihydrofolate reductase in a herpesvirus.

The enzyme dihydrofolate reductase (DHFR) is found ubiquitously in both prokaryotes and eukaryotes. It is essential for de novo synthesis of purines and of deoxythymidine monophosphate for DNA synthesis. Among viruses, however, only the T-even and T5 bacteriophage have been found to encode their own DHFR. In this study a gene for DHFR was found in a specific subgroup of the gamma or lymphotropic class of herpesviruses. DNA sequences for DHFR were found in herpesvirus saimiri and herpesvirus ateles but not in Epstein-Barr virus, Marek's disease virus, herpes simplex virus, varicella-zoster virus, herpesvirus tamarinus, or human cytomegalovirus. The predicted sequence of herpesvirus saimiri DHFR is 186 amino acids in length, the same length as human, murine, and bovine DHFR. The human and herpesvirus saimiri DHFRs share 83 percent positional identity in amino acid sequence. The herpesvirus saimiri DHFR gene is devoid of intron sequences, suggesting that it was acquired by some process involving reverse transcription. This is to our knowledge the first example of a mammalian virus with a gene for DHFR.

The gait abnormality of Huntington's disease.

We investigated 13 patients with Huntington's disease and assessed gait by filming and by gait analyzer before and after increasing haloperidol dosage, until chorea was suppressed or side effects intervened. The severity of chorea and ataxia was scored blindly from videotapes. Gaits were abnormal in 12 of 13 patients and 5 of 6 patients who had symptoms for less than 5 years. Clinical characteristics included wide-based station, lateral swaying, spontaneous knee flexion, variable cadence, and parkinsonian features. Biomechanical analysis illustrated that gait characteristics varied in each walk, with a mean decrease in velocity, stride length, and cadence. Haloperidol treatment decreased chorea but did not affect gait patterns. Ataxia occurs early in the disease, has a distinct but variable pattern, is unrelated to chorea, and is not improved by haloperidol.

Rapid chemical dehydration of biologic samples for scanning electron microscopy using 2,2-dimethoxypropane.

Acidified 2,2-dimethoxypropane (DMP) has been used as a rapid chemical dehydrating agent en route to plastic embedding and ulthrathin sectioning for conventional electron miscroscopy (J Histochem Cytochem 23:107, 1975). We have used DMP to dehydrate biologic specimens prior to critical point drying and metal coating for scanning electron microscopy. There is no difference in either the gross architecture or the fine surface structure of mouse small intestine and trachea, rat trachea and kidney, and cultured fibroblasts, between samples dehydrated in DMP for 5 min to 30 days and those conventionally dehydrated in ethanol or acetone. DMP dehydration is advantageous in speed, economy and apparent completeness.

Electro-oculography in infants.

To record the electro-oculogram in infants without using general anesthesia and passive globe rotation, we used the static vestibular reflex in which compensatory eye movements occur in response to angular rotation of the semicircular canal. To produce these eye movements, we placed the infant in a supine position in his mother's arms in a rocking chair and, while he nursed from a bottle, directed his attention to a distracting stimulus. We recorded the electro-oculogram during rocking under conditions of light and dark adaptation. We used the electro-oculograms to calculate the conventional light-to-dark amplitude ratio.

The effect of mannitol infusion on retinal function and oxygen tension.

Mannitol administered intravenously in rhesus monkeys resulted in a temporary recovery of the visual evoked response (VER) after its decrease due to elevation of the intraocular pressure. Mannitol infusion caused an immediate, albeit transitory, increase in retinal oxygen tension. These changes were independent of the ocular hypotensive effect of mannitol, and we conclude that the drug is a far better agent for the treatment of acute glaucoma than heretofore believed.

Substituted naphthalenones as a new structural class of HIV-1 reverse transcriptase inhibitors.

A novel substituted naphthalenone (TGG-II-23A) has been found that inhibits HIV-1 infection of CEM-SS cells at concentrations that are not cytotoxic. Time of addition experiments indicate that TGG-II-23A functions at a stage of the HIV-1 life cycle at or near reverse transcription. Cell free assays confirmed that TGG-II-23A inhibits HIV-1 reverse transcriptase. Similar to other non-nucleoside inhibitors, TGG-II-23A was specific for HIV-1 and failed to inhibit the replication of HIV-2. The binding site of TGG-II-23A appears to be in close proximity to that of the TIBO-like inhibitors, since a TIBO-resistant HIV-1 was also resistant to TGG-II-23A treatment. TGG-II-23A is a mixed non-competitive inhibitor that exhibits the same template:primer selectivity as other non-nucleoside inhibitors. TGG-II-23A therefore represents a new structural entry into the TIBO/Nevirapine class of inhibitors of HIV-1 reverse transcriptase.

The ecology of Colorado tick fever in Rocky Mountain National Park in 1974. II. Infection in small mammals.

Field studies of Colorado tick fever (CTF) in small mammals in Rocky Mountain National Park (RMNP) in 1974 established that Eutamias minimus and Spermophilus lateralis were the most important hosts for CTF virus and were the source of virus for immature stages of the tick vector, Dermacentor andersoni. Other species (Peromyscus maniculatus, Spermophilus richardsonii, Eutamias umbrinus) are secondary hosts. The intensity of viral activity in rodents varied greatly from locality to locality. Highest rodent infection rates were found to occur in the Moraine Park area of RMNP. Lowest infection rates occurred above 3,290 meters in altitude at Rainbow Curve and on the tundra. The prevalence of infection in rodents was constant from April--July (5--6% of animals captured were viremic) and then declined to 1.7--2.5% in August and September coincident with a decline in nymphal tick ectoparasitism. Many animals were captured which were simultaneously viremic and antibody-positive. Under field conditions, neutralizing antibody seroconversion does not always occur.

Cutaneous pigmentation secondary to amiodarone therapy.

Amiodarone (Cordarone) is an iodinated cardiac antiarrhythmic drug that causes a slate-gray discoloration of the sun-exposed skin and a yellow-brown stippling of the cornea. Histopathologically, biopsy specimens of aminodarone pigmentation sites disclose yellow-brown refractile granules in the reticular dermis. These granules were characterized by transmission electron microscopy as being concentrically arranged intralysosomal inclusions ("myelinlike" bodies) in dermal endothelial cells and perivascular smooth-muscle cells. Electron probe x-ray analysis of these same inclusions disclosed definite peaks for iodine, evidence for the presence of amiodarone or a metabolite of the drug at these sites. Amiodarone, then, concentrates in lysosomes and causes an accumulation of lipids similar to what has been seen with other cationic amphiphilic compounds, such as the glycosphingolipid stored in Fabry's disease. Amiodarone must be recognized as a cause of a drug-induced lipid storage disease with cutaneous and corneal manifestations.

Substance abuse among Native-American youth.

Substance use and abuse poses serious risks for American-Indian youth, their families, and their communities. This article briefly reviews the relevant social epidemiological data followed by a discussion of culturally relevant etiological factors. Current strategies for identification of youth at high risk for substance use are highlighted, concentrating primarily on the theoretical and methodological aspects appropriate for this population. In this context, data from recent work are reported. Given the nascent state of culturally appropriate prevention technology, issues of sensitive technology transfer and stereotyping are discussed in the context of current research. Study results from this sample, although dramatic, should not be overgeneralized to all American-Indian youth.

Identification of fatty acid amides in human plasma.

A family of five long-chain fatty acid carboxamides has been identified and semi-quantified in human plasma by GC-MS. One saturated and four unsaturated amides were found. Luteal phase plasma from 16 women was studied, and all five of the amides were found in ten of the subjects, but none in the other six. The structure of these endogenous amides was established by comparing their GC and MS characteristics with those of the synthetic amides prepared by ammonolysis of corresponding long-chain fatty acid acyl chlorides.

Adult-onset hemiplegia: changes in gait after muscle-balancing procedures to correct the equinus deformity.

Fifty-four adult patients with acquired spastic equinus and equinovarus deformity were treated with lengthening of the Achilles tendon, lateral transfer of the anterior tibial tendon, and appropriate muscle releases. All patients had preoperative dynamic electromyography and electrogoniometry performed in order to assist in planning the surgical procedures and to provide a baseline assessment of the dynamic deformities. Preoperatively, the stance and double-support phases of gait were prolonged. Throughout the stance phase, the gait of these patients was characterized by equinus deformity of the ankle, decreased flexion of the knee (hyperextension in the most severely involved patients), and increased flexion of the hip (which also varied with the severity of the equinus deformity of the ankle and hyperextension of the knee). In all patients, the operation was performed at least one year after onset of the hemiplegia. Clinical follow-up at an average of thirty months (range, twenty-four to sixty-two months) showed that the equinus deformity was corrected in all patients and that 59 per cent of them were brace-free. Two patients had a superficial infection that healed uneventfully, and two had pull-out of the tendon that required reoperation. Postoperative analyses of gait, performed at least one year after surgery for twenty-seven of the patients, showed that the stance and double-support phases of gait (which had been prolonged before surgery) approached the findings in normal control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

The embryological development and cytodifferentiation of the pars distalis of the golden hamster (Mesocricetus auratus). A light and electron microscopic study.

The embryological development of cytodifferentiation of the hamster pars distalis was investigated using light and electron microscope techniques in order to obtain basic information for comparison with pituitary development in other mammalian species. The normal chronological events in the development of the hamster pars distalis closely paralleled the pituitary organogenesis of other laboratory rodents. Rathke's pouch formed and touched the infundibulum at 8 1/2 days of gestation and separated from the stomodeum 3 days later. Penetration of vascular elements from the developing hypophysial portal system into the pars distalis occurred at 12 1/2 days gestation. This was also the first day that small secretory granules were seen in any of the parenchymal cells. Further cytodifferentiation during the following prenatal, and first few postnatal days of life revealed granulated cells which, in most cases, could not be identified using morphological criteria or granule size as may be done in the adult. An orderly sequence of inductive and morphological events appears to take place in the developing hamster adenohypophysis paralleling similar events observed in other animals.

Isolation, selection, and characterization of lactic acid bacteria for a competitive exclusion product to reduce shedding of Escherichia coli O157:H7 in cattle.

Lactic acid bacteria (LAB) were selected on the basis of characteristics indicating that they would be good candidates for a competitive exclusion product (CEP) that would inhibit Escherichia coli O157:H7 in the intestinal tract of live cattle. Fecal samples from cattle that were culture negative for E. coli O157:H7 were collected. LAB were isolated from cattle feces by repeated plating on deMan Rogosa Sharpe agar and lactobacillus selection agar. Six hundred eighty-six pure colonies were isolated, and an agar spot test was used to test each isolate for its inhibition of a four-strain mixture of E. coli O157:H7. Three hundred fifty-five isolates (52%) showed significant inhibition. Seventy-five isolates showing maximum inhibition were screened for acid and bile tolerance. Most isolates were tolerant of acid at pH levels of 2, 4, 5, and 7 and at bile levels of 0.05, 0.15, and 0.3% (oxgall) and were subsequently identified with the API system. Lactobacillus acidophilus, Lactobacillus fermentum, Lactobacillus delbreukii, Lactobacillus salivarius, Lactobacillus brevis, Lactobacillus cellobiosus, Leuconostoc spp., and Pediococcus acidilactici were the most commonly identified LAB. Nineteen strains were further tested for antibiotic resistance and inhibition of E. coli O157:H7 in manure and rumen fluid. Four of these 19 strains showed susceptibility to all of the antibiotics, 13 significantly reduced E. coli counts in manure, and 15 significantly reduced E. coli counts in rumen fluid (P < 0.05) during at least one of the sampling periods. One of the strains, M35, was selected as the best candidate for a CEP. A 16S rRNA sequence analysis of M35 revealed its close homology to Lactobacillus crispatus. The CEP developed will be used in cattle-feeding trials.

Somatosensory evoked potentials, cerebral blood flow and metabolism following cerebral missile trauma in monkeys.

Somato sensory evoked potentials (SEP), cerebral blood flow and cerebral metabolism were studied in seven rhesus monkeys before and after a right occipito-frontal missile injury with an air rifle. The sensory evoked potential was present shortly after injury though markedly altered in shape. There was a very close correlation (r2 equal to 0.83) between SEP and cerebral blood flow on the uninjured side five minutes after injury. On the injured side, this was also noted but the amplitude of the SEP was much smaller, perhaps due to direct injury. If the flow in either hemisphere fell below 15-20 mls/100 gm/min, the evoked response disappeared, but in several animals a subsequent increase in flow was associated with a return of electrical activity. There was no correlation with cerebral perfusion pressure or cerebral metabolic rates for oxygen or lactate production, though it is likely that this is not due to physiological reasons but rather methodological. It might be inferred from these results that adequate flow is vital for the preservation and return of electrical activity following brain injury.

Cytochemical characterization of tegument membrane-associated carbohydrates in Taenia crassiceps larvae.

The tegument of larval Taenia crassiceps possesses a surface coat rich in both neutral and acidic carbohydrates. Neutral glycans were detected in Golgi vesicles of the tegument perikarya, vesicles of the distal tegument, and on the surface of the plasma membrane. Autoradiographs indicated the tegument perikarya as major sites of 3H-galactose incorporation into acid-insoluble macromolecules. The labeled material is subsequently translocated to more superficial regions of the tegument, then concentrated in the brush border. Loss of radioactivity is appreciable within 6 hr of the synthesis of this material, indicating continual replacement of this tegument surface component.

Characterization of the tumor-associated 38-kd protein of herpes simplex virus type 2.

The BglII N DNA fragment of herpes simplex virus type 2 (HSV 2), which is capable of oncogenically transforming cells in vitro, encodes a 37,800-dalton (38-kd) protein that has been seroepidemiologically associated with uterine cervical carcinoma. Polyclonal monospecific antiserum was produced against electrophoretically purified 38 kd from HSV 2-infected cells and used to identify antigenic and biochemical characteristics of the protein as well as to probe transformed cells for the expression of viral 38 kd. The HSV 2 type specificity of the 38-kd protein, previously shown using anti-HSV 2 serum and monoclonal antibodies, was confirmed using anti-38-kd serum. The 38-kd protein of HSV 2 produced in vivo and in vitro displayed type specificity and showed no evidence of posttranslational processing. The 38-kd protein has a relative isoelectric point of 9.1, is synthesized at a maximum level four hours after infection and appears to be a component of the virion. When 35S-methionine radiolabeled 38 kd was immunoprecipitated by anti-38-kd serum, high-molecular-weight proteins (118-140 kd) were also present. However, if prior to reacting with the anti-38-kd serum the high-molecular-weight proteins were separated from 38 kd with sodium dodecyl sulphate-polyacrylamide gel electrophoresis, the only reaction observed with immunoblot was with 38 kd. Therefore, the observed coprecipitation appears to result from the formation of a complex between the proteins and is not the result of shared antigenic determinants. Cells transformed by inactivated HSV 2 were examined for the expression of the 38-kd protein using immunoenzymatic staining. The viral 38-kd protein was not consistently found, but since the protein is reported to be a component of the viral enzyme complex ribonucleotide reductase, it cannot be excluded from possible HSV 2 transformation.

Measuring gait-related blind mobility performance.

The gait characteristics of blind travelers can provide information about their mobility skills. Previous attempts at measuring these characteristics have suffered because they either do not provide continuous monitoring or allow usage outside a laboratory setting. A new instrument has been developed to overcome these problems. The instrument allows continuous monitoring of interankle distance during walking. Records of interankle distance were analyzed to determine maximum interankle distance/step, step time, and cadence. With this system, gait parameters revealed differences between two groups of travelers (blind and blindfolded) and changes over a series of four trials on turns, straightaways, and over the whole route. This suggests the system is useful as an assessment device both for research and for rehabilitation training.

Inkbraille as a potential new reading system for the blind.

Inkbraille, a reduced size ink-image version of the familiar braille code, was conceived in an attempt to sidestep the major disadvantages of embossed braille, while retaining the unsurpassed reading rates achieved by the blind using that code. Inkbraille would ultimately be translated by a specially designed hand-held electronic device with appropriate tactile output. Such a device is not yet available, so in this study we test the readability of Inkbraille when read by means of a commercially available electronic reading aid, the Optacon, which presents its output tactually on a field of vibrating pins which are sensed with a finger. Three modes of tactual reading were compared: conventional embossed braille, and the Opticon's vibrating-pinfield presentation of typed letters and its presentation of Inkbraille. All subjects were able to read Inkbraille upon initial exposure. Subjects who were tested in multiple sessions exhibited significant increases in Inkbraille reading rates after only limited exposure. Since Inkbraille and letterprint reading rates were the same in this study, the results led the authors to conclude that a rate limitation may have been imposed by the device (the Optacon) that was used to translate both the Inkbraille and the letterprint.

Text-scanning patterns of blind readers using Optacon and braille.

Tactual reading usually requires the coordinated use of the forearm/hand motor and tactile sensory systems. Therefore, in a series of studies of tactual reading behavior, we chose to record the text-scanning patterns of adult blind readers in an attempt to gain further insight into the nature of this process. Reading behavior for four modes of tactual reading was recorded (embossed braille one-hand, embossed braille two-hands, Optacon/letterprint, and Optacon/Inkbraille) by detecting and recording the instantaneous position of light-emitting diodes unobtrusively attached to the finger(s) or the Optacon camera. In addition to the comparative evaluation of the four sets of reading patterns, the salient features of the Optacon/letterprint patterns were quantitatively analyzed in an attempt to characterize this particular mode of reading. The text-scanning patterns of Optacon readers have not been previously reported. In general the text-scanning behavior for all modes of tactual reading seems to be similar; the only remarkable difference appears to be in the reading rates. Regarding Optacon/letterprint performance, reading rate was found to be significantly and negatively correlated with line-changing time and the number of regressions. No significant correlation was evident between rate and regression magnitude.

Qualitative and quantitative gait phase analysis by continuous monitoring of inter-ankle distance.

A new device is presented that is able to provide a temporal recording of gait as well as a continuous qualitative monitoring of gait events. It can be used with motor-point electromyography to perform walking electromyography, with an electrogoniometer to record joint position, or with other measuring devices to record events relative to phase of gait. The major advantages of this system as compared with available systems are ease of use, decreased patient encumbrance, potential for portability, greatly reduced expense, and the potential for digitizing the signal for computer compatibility. Preliminary data are comparable to available accepted norms.