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J T Vaughan

Publications and source records attributed to J T Vaughan.

At least 37 records · Page 2Linked to original sources
PubMed1994

Evaluation of cerebral gray and white matter metabolite differences by spectroscopic imaging at 4.1T.

Using a 4.1T whole body system, we have acquired 1H spectroscopic imaging (SI) data of N-acetyl (NA) compounds, creatine (CR), and choline (CH) with nominal voxel sizes of 0.5 cc (1.15 cc after filtering). We have used the SI data to estimate differences in cerebral metabolites of human gray and white matter. To evaluate the origin of an increased CR/NA and CH/NA ratios in gray matter relative to white matter, we measured the T1 and T2 of CR, NA, and CH in gray and white matter using moderate resolution SI imaging. In white matter the T2s of NA, CR, and CH were 233 +/- 27, 141 +/- 18, and 167 +/- 20 ms, respectively, and 227 +/- 27, 140 +/- 16, and 189 +/- 25 ms in gray matter. The T1 values for NA, CR, and CH were 1267 +/- 141, 1487 +/- 146, and 1111 +/- 136 ms in gray matter and 1260 +/- 154, 1429 +/- 233, and 1074 +/- 146 ms in white matter. After correcting for T1 and T2 losses, creatine content was significantly lower in white matter than gray (P < 0.01, t-test), with a white/gray content ratio of 0.8, in agreement with biopsy and in vivo measurements at 1.5 and 2.0T.

Aspartic Acid↗
PubMed1991

Fast short-tau inversion-recovery MR imaging.

To enhance the versatility of the short-tau inversion-recovery (STIR) sequences, the authors determined a range of repetition time (TR) and inversion time (TI) combinations that suppress signal intensity from fat by study of both patient and phantom images. To make fast STIR images, variations in the following pulsing conditions were studied with use of an interactive computer program: decreasing the TR, limiting the number of excitations, and limiting the number of phase-encoding steps. The authors found that (a) STIR imaging need not be time consuming, (b) fat suppression can be accomplished at shorter TR by using shorter TI, and (c) short-TR fast STIR imaging is sensitive to enhancement with gadopentetate dimeglumine.

Humans↗
PubMed1991

Effects of the fungal endophyte Acremonium coenophialum in fescue on pregnant mares and foal viability.

Effects of the endophyte Acremonium coenophialum in tall fescue on pregnant mares and foal viability were evaluated. Twenty-two mature pregnant mares were randomly chosen to graze either Kentucky-31 tall fescue that was free from A coenophialum (endophyte-free, EF) or tall fescue infected with A coenophialum (endophyte-present, EP) after the first 90 days of pregnancy through parturition. Concentrations of pyrrolizidine and ergopeptine alkaloids were significantly greater in EP grass, compared with EF pasture. Ten of 11 mares grazing EP pasture had obvious dystocia. Mean duration of gestation was significantly greater for the EP group, compared with the EF group. Foal survivability was severely reduced among mares grazing EP fescue with only 1 foal surviving the natal period. Udder development and lactation were low in mares grazing EP grass. The absence of clinical problems in mares grazing EF grass implicated the endophyte as the causative agent of reproductive problems and perinatal foal mortality in pregnant mares grazing endophyte-infected fescue grass. Caution should be exercised in allowing pregnant mares to graze pastures infected with the endophyte A coenophialum.

Acremonium↗
PubMed1990

Multinuclear NMR investigations of probe construction materials at 4.7 T.

Since background signal from NMR probes can overwhelm the signal from a sample, the NMR analysis of plastics or machinable ceramics is a prerequisite to their use in probe implementations. The contributions from a variety of materials to proton, fluorine, and carbon NMR spectra are presented.

Electricity↗
PubMed1988

Surgery of the penis and prepuce.

Treatments of penile and preputial injuries, anomalies, tumors, "summer sores," paraphimosis, phimosis, and priapism are presented. Surgical procedures described include preputiotomy, reefing, penile retraction, amputation, and relocation. Treatment of hemospermia by means of urethrotomy is discussed.

Animals↗
PubMed1985

Electroencephalographic patterns of clinically normal, sedated, and tranquilized newborn foals and adult horses.

To establish a clinically practical procedure for recording the equine EEG, 25 healthy adult horses and 6 newborn foals were used. Recordings were taken with the animals alert and tranquilized, confined in metal stocks, or physically restrained. The dominant alert waveforms of adult horses were fast activity (25 to 40 Hz) with medium-to-low voltages (5 to 40 microV-dominant 10 to 15 microV). Underlying this fast activity was slower (0.5 to 4.0 Hz) activity with medium-to-low voltages (10 to 40 microV). Twelve of the 25 adult horses had EEG frequencies in the alpha frequency range (10 to 15 Hz, 10 to 50 microV). Eight horses were given xylazine and 17 were given acetylpromazine. Those given xylazine had generalized slowing with several distinct frequency patterns (25 to 40 Hz, 5 to 30 microV; 10 to 15 Hz, 10 to 80 microV; and 0.5 to 4.0 Hz, 10 to 90 microV). Horses given acetylpromazine had fast activity (25 to 40 Hz) with medium-to-low voltages (5 to 40 microV). Underlying this activity were slower waveforms (1 to 4 Hz) with medium-to-low voltages (5 to 10 microV). Occasional well-formed spindle activity was observed (10 to 14 Hz, 10 to 50 microV). Acetylpromazine had little effect on the EEG recording, whereas xylazine exerted a substantial effect. All leads were synchronous with lower voltages in the left frontal, right frontal, and transfrontal leads. The alert pattern of a newborn foal was characterized by low frequency (2 to 6 Hz) with medium-to-high voltages (20 to 90 microV).(ABSTRACT TRUNCATED AT 250 WORDS)

Acepromazine↗
PubMed1980

Effects of denervation of the digit of the horse.

A study was conducted in an effort to explain why digital necrosis sometimes follows neurectomy in the horse. Six horses were subjected to unilateral section of the medial and lateral palmar nerves. Arteriography was done on each digit prior to surgery. Terminally, arteriography was repeated. Sections of bone, nerve, artery, skin, coronary band, and deep flexor tendon were examined histologically. Changes in arterial pattern and bone quality were noted. During the study, 2 of the horses had clinical signs of digital necrosis. The composite findings suggested trauma or infection, or both, of the denervated digit as the main cause(s) of the digital necrosis. Osteolysis was believed to be the primary contributing factor in disruption and collapse of the supporting structures of the foot.

Animals↗
PubMed1980

Vascular anatomy and surgical technique for bilateral adrenalectomy in the equid.

The vascular anatomy of the adrenal glands and a surgical technique for bilateral adrenalectomy in the equid are described. Bilateral adrenalectomy was performed in six ponies and one horse via bilateral transcostal retroperitoneal approaches through the 18th rib during a single anesthetic period. Complications included hemorrhage from the right side only and pneumothorax which usually occurred on the right side. One pony died as a result of the surgical technique. Maintenance of adrenal function was accomplished with desoxycorticosterone pivilate and prednisolone.

Adrenal Glands↗
PubMed1980

Thermography: a technique for subclinical diagnosis of osteoarthritis.

Thermographic and radiographic evaluations of the tarsus (hock) were done on 20 Standardbred racehorses before and after exercise at three consecutive 6-week intervals. All horses were from the same stable and given the same care and training under identical schedules and conditions. Normal thermographic patterns were established before and after exercise. These patterns corresponded to the underlying tarsal vasculature. Postexercise thermal patterns indicated a warming trend, and the increases were uniform. Abnormal thermal patterns were more localized and did not conform to the normal underlying vascular distribution. Five of the 20 horses trained successfully and competed professionally, with 1 of the 5 showing abnormal thermographic changes. Four horses were too slow to race, and all of these had abnormal thermographic changes of their tarsi. The medial aspect of the right tarsus was more commonly involved than the lateral in these horses. Only one horse was clinically lame and exhibited thermal increases, as well as radiographic changes in the right tarsus. The remaining horses were removed from training due to miscellaneous causes. It was believed that the four horses that failed to make minimum track times (for racing) suffered discomfort in their tarsi sufficient to impair performance. This problem was attributed to early subclinical inflammatory changes within the joints. Though difficult to recognize radiographically, these early changes were conspicuous as abnormal thermographic patterns typical of inflammation.

Animals↗
PubMed1979

Equine melanoma.

Explore the source record for details and available documents.

Animals↗
PubMed1976

Condylomata acuminata.

A 5-year-old Thoroughbred chestnut mare was presented because of multiple lesions noticed for approximately one year over the vulva and ther perianal areas. Clinically, there were moist warts that stood out because of their whitish color which contrasted strikingly with the surrounding, normally pigmented, uninvolved skin (Fig. 1). Repeated topical applications of 20% podophyllin in 95% ethyl alcohol produced rapid involution. Histopathologically, marked acanthosis, numerous mitoses, prominently vacuolated epidermal cells and a chronic dermal inflammatory infiltrate were seen (Figs. 2, 3, and 4). Interestingly, melanin in the basal cell layer was not visible in the lesions, but was very apparent in the normal epidermis at the edges of the lesions. Thus the contrast between the affected and the non-affected skin was also strikingly microscopically (Fig. 2 arrows).

Animals↗