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Biomedical subjects

R T Gordon

Publications and source records attributed to R T Gordon.

13 recordsLinked to original sources
PubMed1992

Active noise control: a review of the field.

Active noise control (ANC) is the application of the principle of the superposition of waves to noise attenuation problems. Much progress has been made toward applying ANC to narrow-band, low-frequency noise in confined spaces. During this same period, the application of ANC to broad-band noise or noise in three-dimensional spaces has seen little progress because of the recent quantification of serious physical limitations, most importantly, noncausality, stability, spatial mismatch, and the infinite gain controller requirement. ANC employs superposition to induce destructive interference to affect the attenuation of noise. ANC was believed to utilize the mechanism of phase cancellation to achieve the desired attenuation. However, current literature points to other mechanisms that may be operating in ANC. Categories of ANC are one-dimensional field and duct noise, enclosed spaces and interior noise, noise in three-dimensional spaces, and personal hearing protection. Development of active noise control stems from potential advantages in cost, size, and effectiveness. There are two approaches to ANC. In the first, the original sound is processed and injected back into the sound field in antiphase. The second approach is to synthesize a cancelling waveform. ANC of turbulent flow in pipes and ducts is the largest area in the field. Much work into the actual mechanism involved and the causal versus noncausal aspects of system controllers has been done. Fan and propeller noise can be divided into two categories: noise generated directly as the blade passing tones and noise generated as a result of blade tip turbulence inducing vibration in structures. Three-dimensional spaces present a noise environment where physical limitations are magnified and the infinite gain controller requirement is confronted. Personal hearing protection has been shown to be best suited to the control of periodic, low-frequency noise.

Ear Protective Devices↗
PubMed1989

Bleeding patterns with low-dose, monophasic oral contraceptives.

Cycle control over 12 months with low-dose oral contraceptives (OCs) was analyzed using calendars of bleeding on pill-taking days 1 through 21 (intermenstrual bleeding; IMB). One preparation contained 0.5 mg norethindrone and 0.035 mg ethinyl estradiol (NET + EE), the other 0.3 mg norgestrel and 0.03 mg ethinyl estradiol (Ng + EE). Half the subjects had previously used OCs containing greater than or equal to 0.05 mg estrogen (switch-over); the others had not previously used OCs for 2 months or more (fresh). Fresh subjects reported more IMB than switch-over subjects, especially during the first three cycles; IMB decreased over time for both groups. Ng + EE subjects had fewer IMB episodes during the early cycles than NET + EE subjects. Daily incidence of IMB formed a characteristic W-shaped curve in the NET + EE subjects that was most apparent in early cycles.

Adolescent↗
PubMed1979

A new right ventricular cardiac assist device.

At present no good method of assisting the right ventricle of the heart exists. This paper presents a new and effective approach to assisting the right ventricle of the heart which can be utilized independently or during cardiac surgery. Through implementation of this method, and timed inflation and deflation of several types of balloon catheters in the pulmonary artery, distal pulmonary arterial flow is augmented with subsequent unloading of the right side of the heart. This approach will be of great benefit in the treatment of atherosclerotic and congenital heart disease as well as in many cases of pulmonary hypertension.

Assisted Circulation↗
PubMed1979

Resonance induced alterations of intracellular biophysical properties.

A treatment of cancer by the application of external electromagnetic energy at a resonant frequency capable of the generation of heat intracellularly to induce selective thermal death of cancer cells is described. This process also allows for the detection of cancer cells by the use of differential resonant frequencies including nuclear magnetic resonance and electron spin resonance techniques. This process permits the selective treatment of cancer cells by the compartmentalized alteration of biophysical properties in the cancer cells and the detection of cancer cells by determination of their biophysical properties. The process comprises an ability to determine the respective resonant frequencies of cancer cells and normal cells at a cellular level. An external alternating electromagnetic field is then applied at the resonant frequency of the cancer cells which differs from the resonant frequency of the normal cells. The cancer cells absorb significant energy at this resonant frequency whereas the normal cells absorb minimal energy at this frequency. Generating the heat intracellularly instead of extracellularly results in the cell's membrane, which is an effective thermal barrier, enhancing the process by keeping the heat within the cell instead of outside of the cell. This process is enhanced by the nuclear differences between cancer cells and normal cells and by the energy changes characteristic of structural and conformational changes in the deoxyribonucleic acid and the histones of the nucleus including their interrelationship. This process promises great efficacy in the diagnosis and the treatment of neoplastic and also perhaps of artherosclerotic diseases.

Arteriosclerosis↗
PubMed1979

Intracellular hyperthermia. A biophysical approach to cancer treatment via intracellular temperature and biophysical alterations.

This paper introduces a new multi-disciplinary "intracellular" biophysical treatment of cancer. The basic concept uses locally induced heat energy after tumor phagocytosis of submicron particles whose composition permits magnetic excitation. The key to this process is the utilization of the cancer cell membrane to contain the energy within the cancer cell. Any magnetic or electric dipole contained within or introduced into the cell, or that is capable of being produced by an external field, can be used. Submicron particles are colloidally suspended, injected intravenously and are phagocytized by cancer cells. Application of an external high frequency or pulsed electromagnetic field then raises the particles' temperature thus generating intracellular heat in precise increments. This results in selective thermal destruction of cancer cells with little effect on normal cells. Experimental evidence is presented showing tumor cell destruction in spontaneous mammary tumors in Sprague Dawley rats. In addition, we suggest that certain biophysical properties are altered within the cancer cells and could be used to enhance this effect. Specific radioisotopes or tumor specific antibodies bound to particles or chemotherapeutic microspheres increase cancer cell sensitivity and affinity for these particles. This "intracellular" treatment of cancer has a wide potential range of applications.

Animals↗
PubMed1979

"Neuro-cardiovascular" surgery: innovations for the treatment and prevention of cardiovascular disease.

The concept of performing surgery on the conduction system and the nervous system of the heart with the use of peripheral nervous tissue, Purkinje fibers or biophysical means, may solve many enigmas concerning the treatment of arrythmias. More importantly, a correlation is suggested between coronary artery disease, the state of depolarization of the myocardial cells, local electrical and magnetic fields, the state of local innervation of coronary blood vessels, the activity of the specialized conducting system, and higher central nervous system centers. This suggested correlation may contribute significantly in the treatment, and eventually, in the prevention of coronary artery disease.

Arrhythmias, Cardiac↗
PubMed1978

Lipoma of the colon.

Lipoma, an uncommon tumor in the gastrointestinal tract, occurs most often in the colon. The majority are asymptomatic but may cause abdominal pain, obstruction, or bleeding. The diagnosis can be made roentgenographically but is usually not made until operation is performed. Small lipomas may be removed by colonoscopy or followed conservatively after biopsy via colonoscopy. The treatment for symptomatic or large lipomas is surgical excision.

Aged↗
PubMed1977

Phytobezoar: a recurring abdominal problem.

Phytobezoars often follow gastric surgery for peptic ulcer disease. Billroth I resections have a high incidence of gastric bezoars, especially if accompanied by vagotomy. The larger opening of a Billroth II resection may result in intestinal bezoars with obstruction in the narrow terminal ileum. Gastric bezoars can be treated with enzymes or can be broken up by endoscopy; only rarely is operative removal required. Intestinal bezoars can be treated by long-tube and enzyme instillation but usually require laparotomy. If possible, the bolus should be milked into the cecum, but enterotomy or even resection may be required. Prevention is the best treatment and can be carried out by instructing patients who have had gastric surgery to avoid the fibrous portion of oranges and grapefruit and to avoid persimmons.

Adult↗
PubMed1976

Cystosarcoma phyllodes metastatic to a brenner tumor of the ovary.

A patient had cytosarcoma phyllodes that developed metastases to bone and to a Brenner tumor of the ovary. The original breast tumor was reported as benign, but the patient died of metastases four months following mastectomy. The rapid growth in the ovary may have been due to estrogenic stroma in the Brenner tumor. This is the first report, to our knowledge, of cystosarcoma phyllodes metastasizing to another tumor.

Bone Neoplasms↗
PubMed1976

Postbulbar peptic ulceration of the duodenum.

One hundred and twenty patients operated upon for peptic ulcer diathesis had intraluminal digital examination of the duodenum seeking post-bulbar ulcers. Twelve such ulcers were found, an incidence of 10 per cent. In six of these patients, the postbulbar ulcer was an unexpected finding, and in two patients, a second ulcer was present. A review of the patients with postbulbar ulcers revealed that these patients had severe ulcer symptoms that responded poorly to medical management. Our patients were treated by truncal vagotomy and an outlet procedure. In ten patients, the anterior duodenotomy was extended to include the stenotic area. A Jaboulay gastroduodenostomy was performed in one patient, and duodenoplasty with pyloroplasty in another patient. These 12 patients were observed from one to six years. There were no deaths. Two patients had temporary gastric atony and one patient had a dumping syndrome. Three patients have had possible recurrence of the ulcer, reoperation being required in one patient. It is possible that unrecognized postbulbar stenosis may be a cause of recurrent peptic ulcer following some surgical procedures. To recognize these ulcers, we believe that the duodenum should be inspected by intraluminal palpation in all patients operated upon for peptic ulcer disease.

Adult↗
PubMed1976

Double pyloroplasty and vagotomy for gastric ulcers.

A group of 31 patients with a variety of gastric ulcers were treated by vagotomy, biopsy, oversewing of bleeding points and a wide double pyloroplasty. On patient, a quadriplegic with multiple stress ulcers, rebled and had to undergo resection. He died a month later of progressive respiratory problems. A second quadriplegic died a month after a bleeding episode from myelitis and encephalitis resulting from a gunshot wound of the neck. He had no rebleeding. A third patient died two years after a gastric operation as a result of bronchial carcinoma. He had no recurrence of the ulcer problem. The remaining 28 patients were observed from six months to five years, an average of two and one-half years. There were no recurrences and only minimal untoward symptoms. It would appear that, for this period of observation, vagotomy with double pyloroplasty offers good treatment for patients with benign gastric ulcers.

Adult↗
PubMedDate not supplied

Adenocarcinoma arising in a diverticular abscess of the colon: report of a case.

A case of a patient with adenocarcinoma in an abscess cavity that resulted from perforated diverticulitis of the descending colon is described. Serial barium-enema studies over a nine-year period show the diverticulosis, perforation, abscess cavity, and finally the adenocarcinoma in the abscess cavity. Although it is infrequent, the possibility of carcinoma must be considered in cases of patients who have unhealed pericolonic abscess cavities.

Abscess↗