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Biomedical subjects

H Mark

Publications and source records attributed to H Mark.

At least 37 records · Page 2Linked to original sources
PubMed1985

[Suprathreshold alternating vestibular stimuli in orbiting spacecrafts].

The actual knowledge of the thresholds of stimulation of the otolith organ is reviewed. A vestibular stimulus unknown until now with a value transgressing the threshold has been found. This gravitational force is due to the gravitation of the sun and is caused by the fact that the spacecraft is moving at a different speed with respect to the sun on one side of the orbit than on the other. The problems of vestibular experiments in space and the connection with space motion sickness due to a field of microgravitation in orbiting spacecrafts is discussed.

Gravitation↗
PubMed1984

The values and limitations of deductive analysis and electrophysiological testing in patients with sinoatrial arrhythmias.

We reviewed the values and the limitations of deductive analysis and electrophysiological testing of sinoatrial arrhythmias (SAA). Both methods have a place in the evaluation of SAA and are complementary. Careful analysis of the surface ECG and the response of the sinus node to various tachyarrhythmias and to atrial premature beats can provide important information about the automaticity of the sinus node and sinoatrial and atriosinus conduction. Because of the sporadic nature of some SAA, the surface ECG sometimes must be supplemented by ambulatory ECG recording. This approach improves one's ability to analyze the underlying mechanism and it can also clarify the relation between the SAA and the patient's symptoms. Electrophysiological testing can be employed to reproduce certain SAA and to assess the effects of various drugs on sinus node function. This approach is superior to deductive analysis in the identification of some sinoatrial conduction abnormalities and sinus node reentry. Among the disadvantages of electrophysiological testing are its invasive character and the fact that normal electrophysiological results do not exclude sinus node dysfunction. A definitive clarification of the underlying mechanism of SAA requires direct recording of the sinus node electrogram.

Arrhythmia, Sinus↗
PubMed1984

1984 Bauer lecture. The space station--mankind's permanent presence in space.

The Space Station is a means of furthering mankind's investigation of space and studying his responses to long-duration residency in the environs of space and weightlessness. The historical development of the NASA Space Station is reviewed from President Reagan's announcement of this as a new national commitment. The very tenuous history of the Space Station and it's course through technical/political reviews is the text of this Lecture.

History, 20th Century↗
PubMed1983

Delayed repolarization syndrome.

The electrocardiograms of 18 patients with atypical ventricular tachycardia manifested as torsade de pointes, ventricular fibrillo-flutter, polymorphous ventricular tachycardia, and uniform ventricular tachycardia were analyzed. The patients were divided into two groups: The first group included 10 patients with prolonged Q-T intervals or abnormal U waves (delayed repolarization) and the second group included eight patients with normal ventricular repolarization. All of the electrocardiographic manifestations of atypical ventricular tachycardia were seen in both groups, regardless of the duration of the Q-T interval or the presence of an abnormal U wave. It is suggested that QRS morphology during the tachycardia is not sufficient to distinguish between delayed repolarization and other causes of atypical ventricular tachycardia. Finally, because the electrocardiogram may vary among different patients and from one episode to the next in a single patient due to abnormal repolarization, it is recommended that the term delayed repolarization syndrome be used to identify the arrhythmia.

Adult↗
PubMed1983

[The cause of vomiting in seasickness].

The fact that humans and some mammals vomit when suffering from any kind of motion sickness is explained on a phylogenetic basis. The swim bladder of fish develops from the same embryological origin as the stomach. In a certain group of fish the swim bladder changes its pressure and volume by contraction during sudden upward and downward movements. As the swim bladder is in very close connection with the labyrinth in many fish, it seems absolutely possible that such contraction is caused by a labyrinthine reflex influencing the N, vagus. The contraction of the muscular wall of the stomach in humans--resulting in vomiting--is, therefore, a phylogenetic heritage.

Air Sacs↗
PubMed1981

Extra AV nodal Wenckebach periodicity.

Extra AV nodal Wenckebach periodicity was diagnosed in seven patients. The most frequent form of this conduction abnormality was an exit block. The underlying block was localized in the sinoatrial junction and in the atria in two patients; the AV junction and the ventricle were the site of the Wenckebach periodicity in one case each. In extra AV nodal exit block, the actual conduction delay is not seen on the ECG and the diagnosis is based on the progressive shortening of the P-P or R-R intervals followed by a pause which is less than twice the shortest P-P (R-R) interval depending on the level of the block. A Wenckebach periodicity in the bundle branches or within the reentry pathway each occurred in one patient. In these forms of Wenckebach periodicity, the diagnosis is established more readily because the conduction delay can be demonstrated on the surface ECG. The clinical significance of extra AV nodal Wenckebach periodicity is discussed.

Aged↗
PubMed1978

Combined intra-Hisian block and A-V nodal bypass.

A patient with first and second degree atrio-ventricular (A-V) block and left bundle branch block was shown on electrophysiological study to have an intra and infra-His bundle branch block. In addition, this patient also had an A-V nodal bypass tract. The intra-Hisian block was concealed on the resting His bundle electrogram and became evident only during atrial pacing. The A-V nodal bypass was masked on the surface electrocardiogram (ECG) by the associated A-V conduction defect. The clinical significance of A-V bypass and combined block below the A-V node is discussed. The diagnostic value of His bundle electrocardiography in a patient with complex electrophysiological abnormalities is stressed.

Aged↗
PubMed1977

Juvenile nasopharyngeal angiofibroma. An unusual presentation as an oral mass.

Although juvenile nasopharyngeal angiofibroma (JNAF) usually presents as a mass in the nasopharynx, the primary manifestation may, in rare instances, occur intraorally. We observed such a case in a 12-year-old boy. The clinical finding of hemorrhage from the nasopharynx or contiguous areas in a male adolescent is an important diagnostic clue which should alert the clinician to the possibility of JNAF as the underlying cause.

Child↗
PubMed1975

Clinician attitudes toward the suicide attempter.

The clinical and sociodemographic characteristics and dispositional outcome of 248 suicide attempters were studied in a general hospital emergency room. A mood adjective checklist was completed by evaluating psychiatric residents and three orthogonal factor analytically derived mood clusters were related to sociodemographic, clinical, and dispositional variables. Residents expressed warmth toward patients having low suicide risk and limited overall psychopathology. They felt anxious toward patients with high suicidal risk and significant psychopathology. Angry feelings were reported toward patients with high suicidal risk in the absence of recent precipitating events. Residents reported warmth toward patients admitted to private or mental health center vs. state hospital facilities and tended to devote more time to their clinical assessment of these patients. Feelings of anxiety and anger characterized the responses to state hospital admissions who were only briefly assessed. The findings have implications for the organization of clinical services and the training of mental health professionals. Supervision needs to be directed to the recognition and modification of therapist emotional attitudes as well as to the understanding of patient psychopathology. Clinician feelings can then be effectively utilized to "capture" a high risk, high drop-out population into effective follow-up care.

Age Factors↗