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Biomedical subjects

J R Clark

Publications and source records attributed to J R Clark.

At least 91 records · Page 5Linked to original sources
PubMed1985

Multidisciplinary treatment of advanced squamous carcinoma of the head and neck.

Advanced squamous carcinoma of the upper aerodigestive tract continues to be a therapeutic challenge. With recent advances in chemotherapy, systemic treatment has been used in an attempt to improve treatment results produced by radiation therapy and/or surgery. Such multidisciplinary experimental approaches have given new hope for cure in stage III and stage IV disease, but have reopened old questions as to the natural history and underlying biology of this disease. Multidisciplinary treatment, whether synchronous or sequential, appears to improve survival for stage III and stage IV patients achieving a complete response to chemotherapy plus irradiation. The role of surgery or radiotherapy for control of primary or nodal disease remains unchanged and is an essential component of all curative treatment plans.

Carcinoma, Squamous Cell↗
PubMed1985

Facial paralysis in Lyme disease.

Lyme disease is a multisystemic illness caused by a tick-borne spirochete. Once considered unique to the Connecticut coastline, thousands of cases are now documented throughout the United States, northern Europe, and Australia. Unilateral and bilateral facial paralysis may occur in up to 11% of patients with Lyme disease. This paper reviews the clinical course, distinguishing features, and outcome of 124 such palsies in 101 patients seen between 1975 and 1984. The 99.2% spontaneous recovery rate demonstrates the unequivocally excellent prognosis of this palsy and confirms that operative intervention is not indicated. The otolaryngologist should consider this etiology in all otherwise idiopathic facial paralyses, especially when presenting in summer months in endemic areas, or when bilateral. Positive Lyme disease spirochete titers are helpful in the diagnosis. We believe antibiotics should be given to patients with this facial palsy in order to treat any other concurrent manifestations of the illness and to prevent subsequent complications.

Adolescent↗
PubMed1980

Serum progesterone and corpus luteum function in pregnant pigtailed monkeys (Macaca nemestrina).

Corpus luteum (CL) function and control during pregnancy and early lactation in the pigtailed macaque was investigated. Peripheral concentrations of progesterone (P) on day 10 of pregnancy were 12.98 +/- 2.21 ng/ml and decreased progressively to 7.96 +/- 1.27 ng/ml by day 21 of pregnancy. The concentration of P increased around day 27 of gestation and reached peak levels of 18.48 +/- 2.45 ng/ml on day 37, thereafter gradually decreasing to a nadir at about midgestation. Ten days before parturition P concentrations increased again (P < 0.05). Concentrations of P decreased from 6.62 +/- 1.48 ng/ml on the day of delivery to 2.16 +/- 0.43 ng/ml on day 2 of lactation and remained low thereafter. Ovariectomy on day 35 did not affect the normal course of gestation or the patterns of P secretion during pregnancy. However, in these ovariectomized animals, in spite of suckling, P was not detectable after parturition. In intact monkeys, serum concentrations of P in the utero-ovarian vein at days 80 and 159 of pregnancy were higher relative to the uterine vein. Incubation studies utilizing 3H-cholesterol as a substrate revealed that the CL were capable of synthesizing P on days 35 and 159 of gestation. Histologically, the CL contained active luteal cells at late pregnancy. Low serum concentrations of chorionic gonadotropin were detected on day 10 of gestation; concentrations of this hormone reached high levels between days 18 and 24 and the titers were nondetectable after day 40 of pregnancy. Luteinizing hormone was present in constant amounts in the circulation during pregnancy and lactation. These data suggest that the CL of pregnancy in the pigtailed monkey is functional or capable of functioning during various stages of pregnancy. However, the fetoplacental unit is the primary source of P during the latter 4.5 months of gestation. As in other primates, a functional CL is not required for maintenance of pregnancy after implantation nor for lactation. Thus, the physiological significance of CL function during pregnancy is unclear.

Animals↗
PubMed1979

Luteal phase deficiencies in peripubertal rhesus monkeys: mechanistic considerations.

Short luteal phases in peripubertal monkeys were identified by abbreviated progesterone secretion. Evaluation of the hormonal profiles for LH, FSH, and estradiol revealed that depressed serum concentrations of FSH during the follicular phase and LH and estradiol during the luteal phase were associated with luteal defects. In addition, morphological differences in the corpora lutea of short and normal luteal phases were identified. A mechanism is presented whereby inadequate follicular phase FSH secretion results in abbreviated luteal function.

Animals↗
PubMed1979

Juvenile-onset metachromatic leukodystrophy: biochemical and electrophysiologic studies.

A 15-year-old girl with juvenile-onset metachromatic leukodystrophy (MLD) had markedly decreased leukocyte arylsulfatase A activity and low levels of leukocyte beta galactosidase and serum acid phosphatase. There was marked slowing of nerve condition velocity, and metachromasia was seen in biopsied sural nerve. Leukocyte arylsulfatase A activity was decreased in all members of the girl's family, and sural nerve action potentials were abnormal in two asymptomatic siblings. Electrophysiologic studies combined with biochemical studies may aid in the identification of presymptomatic metachromatic leukodystrophy homozygotes or asymptomatic heterozygotes.

Adolescent↗
PubMed1977

A new method for measuring the amount of correction to be obtained by using a crescentic osteotomy of the first metatarsal.

In performing a crescentic osteotomy of the first metatarsal, it is difficult to determine how far to move the first metatarsal to place it in the ideal position. In this paper, the author presents a new method of measurement which makes it possible for the surgeon to calculate easily the amount of correction necessary and to measure this correction at the time of surgery. His technique eliminates the delay of an x-ray in the operating room before closure.

Humans↗
PubMed1976

Oral hygiene in the orthodontic practice: Motivation, responsibilities, and concepts.

This article describes our current oral health program. This program will continue to change as we learn more effective ways to communicate and offer instruction. The orthodontist and his staff are in a unique position to help patients become concerned about oral health. The cumulative effect of such patient educations is tremendous since hundreds of patients can be affected. Improving the effectiveness of an oral health program is an excellent opportunity to expand our service as health-care practitioners. A survey of dental home-care programs shows that a relationship exists between dentists' attitudes toward their programs and the degrees of success. Usually an oral health program will not become effective unless the orthodontist is motivated and accepts responsibility for motivating his staff and patients. The extent to which an orthodontist is enthusiastic and involves himself in oral health motivation will be reflected in how enthusiastic his auxiliaries are when instructing patients. If an orthodontist delegates both the motivational and instructional aspects of oral hygiene improvement to auxiliaries, his program will fall short of its potential effectiveness. A comment at each appointment telling the patient about his cleaning effectiveness is especially helpful. This feedback should be offered with kindness, objectivity, and respect for the patient. If an orthodontist feels impatient or frustrated, the patient will perceive this; perception of this negativity will frequently result in patient resistance to instruction and cooperation. When an orthodontist offers guidance in oral hygiene with sincere interest and respect, patients usually respond to his concern and become receptive to improving themselves. The extent to which we recognize a patient's "potential" to achieve excellent oral health, regardless of his present condition, will affect our ability to motivate that person. Our respect for patients will increase when we accept that nearly every patient has the inner capability for achieving excellent oral health. We have an opportunity to help patients recognize this potential. When patients recognize more of their potential, self-respect grows and they gain interest in caring for themselves.

Dentist-Patient Relations↗
PubMed1976

A new series of cardioselective adrenergic beta-receptor blocking compounds. 1-(2-Acyl-4-acylaminophenoxy)-3-isopropylaminopropan-2-ols.

A series of 1-(2-acyl-4-acylaminophenoxy)-3-isopropylaminopropan-2-ols has been synthesized and examined for beta-receptor blocking and antiarrhythmic activity. Several of these compounds are more than 20 times as active in blocking cardiac beta-receptors than vascular beta-receptors when given intravenously to anesthetized cats. The activities have been correlated quantitatively with partition and steric substitution constants. The observed relationships are consistent with a tentative proposal that the vascular receptor is situated in a more lipophilic environment than the cardiac receptor so that there is a differential transport effect between the two types of receptor.

Adrenergic beta-Antagonists↗