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A R Kendall

Publications and source records attributed to A R Kendall.

At least 19 recordsLinked to original sources
PubMed2001

Capturing the circadian rhythms of free-running blind people with 0.5 mg melatonin.

We have recently shown that six of seven totally blind people (who had free-running circadian rhythms with periods longer than 24 h) could be entrained (synchronized) to a nightly dose of 10 mg melatonin. After treatment discontinuation and re-entrainment to the 10 mg dose, we further found in three of these subjects that the dose could be gradually reduced to 0.5 mg without loss of effect. The question then arose: can a de novo (starting) dose of 0.5 mg initially capture free-running rhythms? Following withdrawal of the stepped-down 0.5 mg dose and consequent release into a free-run, the same three individuals were given 0.5 mg of melatonin de novo. All entrained within a few weeks.

Adult↗
PubMed2001

Effects of aging on the intrinsic circadian period of totally blind humans.

Age-related changes in the intrinsic circadian period (tau) have been hypothesized to account for sleep symptoms in the elderly such as early morning awakening. The authors sought to determine whether the aging process produced quantifiable differences in the tau of totally blind men who had free-running circadian rhythms. The melatonin onset was used as the indicator of circadian phase. Melatonin rhythms had been characterized about a decade previously when the participants were 38 +/- 6 (SD) years old. Both previous and current assessments of tau were derived from at least 3 serial measurements of the 24-h melatonin profile from which the melatonin onset was determined. All 6 participants exhibited a longer tau in the 2nd assessment (mean increase +/- SD of 0.13 +/- 0.08 h; p < 0.01). Four participants exhibited differences in tau with nonoverlapping 95% confidence intervals. The results do not support the commonly held view that tau shortens during human aging. On the contrary, tau appears to slightly, but significantly, lengthen during at least 1 decade in midlife.

Adult↗
PubMed2000

Entrainment of free-running circadian rhythms by melatonin in blind people.

BACKGROUND: Most totally blind people have circadian rhythms that are "free-running" (i.e., that are not synchronized to environmental time cues and that oscillate on a cycle slightly longer than 24 hours). This condition causes recurrent insomnia and daytime sleepiness when the rhythms drift out of phase with the normal 24-hour cycle. We investigated whether a daily dose of melatonin could entrain their circadian rhythms to a normal 24-hour cycle. METHODS: We performed a crossover study involving seven totally blind subjects who had free-running circadian rhythms. The subjects were given 10 mg of melatonin or placebo daily, one hour before their preferred bedtime, for three to nine weeks. They were then given the other treatment. The timing of the production of endogenous melatonin was measured as a marker of the circadian time (phase), and sleep was monitored by polysomnography. RESULTS: At base line, the subjects had free-running circadian rhythms with distinct and predictable cycles averaging 24.5 hours (range, 24.2 to 24.9). These rhythms were unaffected by the administration of placebo. In six of the seven subjects the rhythm was entrained to a 24.0-hour cycle during melatonin treatment (P<0.001). After entrainment, the subjects spent less time awake after the initial onset of sleep (P=0.05) and the efficiency of sleep was higher (P=0.06). Three subjects subsequently participated in a trial in which a 10-mg dose of melatonin was given daily until entrainment was achieved. The dose was then reduced to 0.5 mg per day over a period of three months; the entrainment persisted, even at the lowest dose. CONCLUSIONS: Administration of melatonin can entrain circadian rhythms in most blind people who have free-running rhythms.

Adult↗
PubMed1991

Computer-assisted microfluorometric detection of individual malignant bladder cells.

A prospective study was done comparing the use of computer-assisted fluorescence photomicroscopy (cytophotometry) with routine cytology for the detection of human bladder cancers. A total of 129 specimens were analyzed from 89 patients. The patients were divided into two groups: Group I, with cancer demonstrated cystoscopically (55 specimens) and Group II, with no demonstrable cancer (74 specimens). The false-negative rate for cytology in the Group I patients was 64 percent but only 7 percent for microfluorometry. The false-positive rate for cytology in Group II was 5 percent but 59 percent for microfluorometry because of the presence of "reactive" cells. The sequential measurement of both routine cytology and deoxyribonucleic acid (DNA) content can be performed on the same cells. When both modalities were employed, the false-negative and false-positive rates were only 4 percent and 5 percent, respectively. The technique and advantages of cytophotometry are discussed in detail, especially in relation to flow cytometry.

Carcinoma, Transitional Cell↗
PubMed1989

Segmental infarct of the testis due to hypersensitivity angiitis.

We present a case of hypersensitivity angiitis causing a segmental infarction of the testis. The lesion presented as a discrete, palpable mass that led to orchiectomy. Hypersensitivity angiitis has not been reported previously to affect the testes or to produce a segmental infarct in any solid organ. A discussion is given of the vasculitides, especially periarteritis nodosa, that may involve the testes.

Humans↗
PubMed1989

Venous intravasation of barium into the inferior mesenteric vein mimicking a coloureteral fistula: a case report and literature review.

Venous intravasation of barium following a barium enema is a rare event. We report a case of barium venous intravasation into the inferior mesenteric vein. Because of the close proximity to the course of the left ureter, this condition was interpreted initially as a coloureteral fistula. After further analysis of the original films, and left retrograde pyelography the true diagnosis was established. A literature review of barium intravasation is presented.

Barium Sulfate↗
PubMed1989

Congenital pelvic arteriovenous malformation with massive prostatic hemorrhage: a case report.

Congenital arteriovenous malformations in the true pelvis are extremely rare: only 7 cases have been described in male patients. We report on a patient who presented with massive hemorrhage after transrectal prostatic biopsy and transurethral resection of the prostate. Diagnosis was established by means of magnetic resonance imaging and confirmed by arteriography. Our attempt at management by embolization and subsequent surgical ligation is described. A literature review and discussion of arteriovenous anomalies are presented.

Aged↗
PubMed1988

Spontaneous subcapsular renal hematoma: diagnosis and management.

Spontaneous subcapsular or perinephric hematoma in the absence of anticoagulation, arteritis or trauma is most likely due to an underlying renal tumor. Eight such patients recently have been evaluated and after nephrectomy 5 had small tumors undetectable by imaging techniques, including computerized tomography or angiography. In 1 patient a tumor was demonstrated preoperatively by angiography and in only 2 was a tumor not found. In the absence of an apparent etiology, patients with spontaneous renal bleeding and a normal contralateral kidney should undergo radical nephrectomy because of the extremely high incidence of small undetectable occult tumors, often less than 2 cm. in size.

Adult↗
PubMed1985

The use of the Nd:YAG laser in urology.

The use of the neodymium:YAG(Nd:YAG) laser in urology in still in its infancy. To date, the most widely published application of this laser is in the treatment of bladder carcinoma. We have utilized the Nd:YAG laser in 23 treatments for superficial bladder tumors. The laser has both advantages and shortcomings, which are thoroughly addressed. In our hands the laser has been a safe instrument for the treatment of these lesions, although we do not recommend its use for tumors greater than 3 cm. We have treated two patients with invasive disease one week prior to planned cystectomy. In one case, no residual tumor was found at cystectomy, while the second patient had viable tumor only in an untreated area. Two patients were successfully treated with the laser for intractable bladder bleeding, one each with primary and secondary bladder tumor. Seven patients with condylomata acuminata were treated with laser therapy. All had excellent results without complication. One patient with urethral bleeding secondary to trauma was treated without success, while one patient with a urethral hemangioma was well treated with the Nd:YAG laser. Thus the Nd:YAG laser would appear to have a place in the urologic armamentarium, but whether it is cost-effective for widespread use remains to be seen.

Carcinoma↗
PubMed1985

Diverticular abscess of colon: irritative bladder symptoms.

Diverticular disease can affect the bladder in subtle ways. Presented herein is a case of a chronic abscess secondary to diverticulitis presenting as irritable vesical symptoms overlooked for several years. The value of pelvic computerized tomography in the diagnosis is stressed.

Abscess↗
PubMed1985

Percutaneous management of a pyelocaliceal diverticular abscess.

A renal abscess secondary to obstruction and infection of a pyelocaliceal diverticulum was managed successfully percutaneously. The diverticulum spontaneously re-established communication with the renal collecting system. No surgery was required and the patient was well 2 years later.

Abscess↗
PubMed1985

Benign prostatic hyperplasia. Evaluation, management, and operative indications.

Although signs and symptoms of benign prostatic hyperplasia are found in an estimated 90% of men by the age of 70, less than 10% are likely to require surgery. If symptoms are mild and findings on urinalysis negative, nothing further need be done except follow-up evaluation in six months. Many patients stabilize without any progression of disease. When treatment is necessary, there is at present no alternative to surgery. Transurethral resection is the preferred procedure. Reoperation is seldom necessary.

Humans↗
PubMed1984

Lasers in urology. I. Laser physics and safety.

Interest in the use of the laser in urology is increasing. A thorough understanding of the physical principles governing the laser will aid greatly in the choice of the proper laser for each indication. The tenets of laser safety are stressed, along with the current federal guidelines.

Environmental Exposure↗
PubMed1984

Lasers in urology. II. Laser therapy.

To date four laser wavelengths are commercially available which have urologic applications. The experience with all of these lasers is reviewed. The major urologic lesions treatable by the laser are: condylomata acuminata, superficial penile carcinoma, and bladder carcinoma. The carbon dioxide (CO2) laser is most applicable for external genital lesions while the Nd:YAG laser is better suited for the endoscopic treatment of bladder tumors. Due to its preferential absorption by hemoglobin, the argon laser is useful in treating vascular lesions. The tunable dye laser with hematoporphyrin-derivative therapy has exciting potential, but is too new to evaluate its therapeutic efficacy.

Argon↗