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Biomedical subjects

C Hamm

Publications and source records attributed to C Hamm.

70 records · Page 4Linked to original sources
PubMed1989

Cerebral blood flow, oxygenation, and carbohydrate metabolism in immature fetal sheep in utero.

Studies of cerebral blood flow (CBF) and metabolism in fetal sheep have been largely confined to late gestation, a time when brain development in this species is largely complete. Few studies have been done at a time when the fetal sheep brain is in the midst of rapid differentiation and development. We studied seven fetal sheep in utero at 91 days of gestation (term = 145-150 days) 24 h after catheters were placed into the sagittal sinus, axillary artery, and inferior vena cava. We measured CBF by the microsphere method and used arteriovenous differences of O2, lactate, and glucose to calculate cerebral O2 consumption (CMRo2), fractional O2 extraction, glucose consumption, O2-glucose index (OGI), and cerebral lactate production. Compared with near-term fetal sheep, we found lower CBF (33.9 +/- 5.3 ml.100 g-1.min-1), lower glucose consumption (8.5 +/- 1.25 mumol.100 g-1.min-1), and lower CMRo2 (41.8 +/- 8.8 mumol.100 g-1.min-1). Fractional O2 extraction was 0.29 +/- 0.04, which is similar to near-term fetal sheep. There was consistent cerebral lactate production (2.45 +/- 1.58 mumol.100 g-1.min-1). The OGI was 81 +/- 16%, i.e., oxidative metabolism could account for 81% of glucose uptake. Lactate production accounts for virtually all glucose uptake exceeding that required for oxidation.

Animals↗
PubMed1988

Recombinant single-chain urokinase-type plasminogen activator during acute myocardial infarction.

Recombinant single-chain urokinase-type plasminogen activator was intravenously administered in 2 different doses in 24 patients with acute myocardial infarction and angiographically proved occlusion of the infarct-related artery. Patients with first infarction without contraindications of thrombolysis were treated within the first 4 hours after the onset of symptoms. Group A (12 patients) received 20 mg of rscu-PA as a bolus followed by 60 mg infused over 1 hour and group B received 10 mg as a bolus and 30 mg as infusion. The 2 groups showed no significant difference in age, sex, height, weight, time between onset of symptoms and start of therapy, peak values and course of infarct-related enzymes. Time to reperfusion was 43 minutes in group A versus 67 minutes in group B (p less than 0.005). The rate of reperfusion 90 minutes after start of treatment was 91% in group A and 50% in group B (p less than 0.001). Plasma levels of fibrinogen, plasminogen and alpha-2-antiplasmin did not differ significantly in both groups. Systemic lytic state (fibrinogen less than 100 mg/dl) occurred in 33% of group A and in 9% of group B. Intravenous infusion of 80 mg (but not 40 mg) of rscu-PA led to reperfusion of the occluded coronary artery in nearly all patients. Approximately one-third of the patients treated with this dose demonstrated systemic lysis.

Adult↗
PubMed1988

Varicella exposure in a neonatal intensive care unit: case report and control measures.

Forty-six infants in a neonatal intensive care unit and 138 health care workers were exposed to a pediatric medical resident during the prodromal period and the early days of unrecognized varicella. An attempt was made to prevent an outbreak of additional cases by the institution of emergency control measures. These measures included rapid identification of varicella antibody status in exposed neonates, varicella antibody testing of health care workers with unknown or uncertain history of varicella, prompt administration of varicella zoster immune globulin to potentially susceptible persons, and cohorting neonates on the basis of exposure and antibody status. Passive maternal antibody was detected in 44 of the neonates. Of 27 health care workers who reported either a negative or an uncertain history of varicella, 26 had detectable antibody. No overt cases of varicella occurred in exposed patients or personnel.

Adult↗
PubMed1987

Fast atom bombardment/tandem mass spectrometry of physalaemin-like peptides.

Fragment ion spectra obtained from collision-induced decomposition of protonated molecular ions have been used to determine amino acid sequences of several physalaemin-like peptides which were recently purified from rabbit stomach. This technique was chosen because the peptides were available in microgram quantities and were anticipated to contain pyroglutamate as the blocked N-terminal residue. Such spectra of several synthetic analogs of the naturally occurring peptides were obtained and analyzed to confirm the veracity of this peptide sequencing strategy. In addition, methyl ester derivatives of these synthetic peptides provided a crucial test for the spectral interpretation via the mass shifts thus induced.

Amino Acid Sequence↗
PubMed1987

Sinoaortic denervation in the nonhuman primate.

There is considerable controversy as to whether removal of baroreceptor input by sinoaortic deafferentation leads to a sustained hypertension in quadripeds. Because of the importance of the baroreflex during postural changes, the effects of baroreceptor denervation may be even more profound in the primate. In this study, six adult male baboons (Papio anubis) were maintained on a tether system to examine the acute and sustained effects of aortic and combined carotid sinus and aortic baroreceptor deafferentation. Mean arterial pressure (MAP) averaged over 24 h increased from 86 +/- 4.0 to 105 +/- 5.5 mmHg after aortic denervation. One week after sinoaortic deafferentation, arterial pressure rose to 129 +/- 12.9 mmHg and then receded to 97 +/- 4.4 mmHg at 4 wk postdenervation. The lability of arterial pressure (measured as the mean of the standard deviations over 24 h) did not change with aortic denervation but increased at 1 and 4 wk after complete baroreceptor denervation. These studies indicate that baroreceptor deafferentation in the primate results in an acute increase in arterial pressure, the lability of arterial pressure, and heart rate. However, by 4 wk postdenervation, the level and lability of arterial pressure are decreased but remain significantly elevated.

Animals↗
PubMed1987

[Left ventricular diastolic function in PTCA: a Doppler echocardiographic study].

The measurement of left ventricular inflow by Doppler echocardiography provides a continuous, non-invasive assessment of parameters of diastolic function. We studied changes in left ventricular diastolic function during percutaneous transluminal coronary angioplasty (PTCA) of the left anterior descending coronary artery (LAD). In ten patients, the diastolic flow velocity profile across the mitral valve was measured by Doppler echocardiography, before and 60 s after inflation and 60 s after deflation of the balloon. The peak velocity of early diastolic filling (VE) significantly decreased during angioplasty, from 68 +/- 12 to 56 +/- 10 cm/s (p less than 0.001), while the peak velocity of late diastolic filling caused by atrial contraction (VA) showed no change. This resulted in a significant decline in the diastolic velocity ratio (VE/VA) from 1.11 +/- 0.47 to 0.92 +/- 0.35 (p less than 0.01). The total area under the diastolic flow velocity profile representing the total filling volume fell from 14.3 +/- 4.1 to 10.9 +/- 3.6 cm (p less than 0.001). The early diastolic filling fraction decreased from 68 +/- 5% to 64 +/- 7%, in favor of the filling fraction due to atrial contraction, which increased from 32 +/- 5%, to 36 +/- 7% (p less than 0.01). 60 s after deflation of the balloon, the parameters of diastolic filling returned to baseline values. We conclude from our results that diastolic dysfunction caused by angioplasty of the LAD results in a decrease in early diastolic left ventricular filling, which is completely reversible after 60 s.

Adult↗
PubMed1986

Physalaemin-like immunoreactive peptides from rabbit stomach.

Two physalaemin (PHY)-like immunoreactive peptides, designated PHLIPs, have been purified from extracts of rabbit stomach tissue. Fast atom bombardment/mass spectrometry (FAB/MS) indicated that the m/z values for the PHLIP protonated molecular ions were 867.419 and 796.4. FAB/tandem MS spectra, coupled with a knowledge of the amino acid composition and the aid of a computerized fragment-matching program, indicated the amino acid sequences to be: (formula; see text) The sequences of PHLIPs-7 and -8 were confirmed with synthetic peptides. The PHY-antiserum cross-reactivity of the PHLIPs reflects homology at amino acid residues 1, 3, 4 and 5 for the mammalian and amphibian residues.

Amino Acid Sequence↗
PubMed1986

Aortic baroreceptor deafferentation in the baboon.

Previous animal studies have indicated that removal of the aortic baroreceptors causes a moderate increase in arterial pressure that is not fully buffered by receptors in the carotid sinus. However, the role of these separate baroreceptors in the conscious nonhuman primate has not been examined. To address this question, adult male baboons were chronically maintained on a tether system that permitted them to move freely about their cage. With this system, arterial pressure and heart rate could be monitored continuously over 24-h periods with periodic drug administration to test cardiovascular function. Control values of arterial pressure and heart rate were 85.6 +/- 4.0 mmHg and 77.5 +/- 2.9 beats/min, respectively. Following removal of the aortic baroreceptors, arterial pressure rose to 104.6 +/- 5.5 mmHg and heart rate increased to 117.9 +/- 3.1 beats/min. The variability of these parameters did not change following denervation. There was, however, a suppression of the arterial pressure-heart period relationship and an augmentation in the depressor response to ganglionic blockade with hexamethonium. These data indicate that removal of the aortic baroreceptors causes a reduction in the sensitivity of the heart rate baroreflex and subsequent increase in arterial pressure that is a result of an increased sympathetic nervous system function.

Animals↗
PubMed1983

[Transureteral endoscopy and its significance for urinary tract infection].

In a period of 10 years transureteral operations were performed on 199 patients. Examinations were carried out periodically in the first 3 months and after 12 months. Pathomorphological changes, subjective symptoms and parameters deviating from normal were noted during urine and serum analyses and subjected to significance tests. Taking the results into consideration it is shown that transureteral endoscopy can induce infection of the urinary passages with its sequelae, and is thus to be seen as a dangerous diagnostic and therapeutic procedure connected with complications.

Bacteriuria↗
PubMed1980

[Significance of myocardial blood flow and metabolism in valvular aortic stenosis for the indication for operation (author's transl)].

Coronary venous blood flow measured by continuous thermodilution, myocardial oxygen consumption and lactate extraction rate were estimated at rest and during graded heart rate exercise in 21 patients with compensated aortic valve stenosis and in 10 patients without heart disease. Significant differences between the groups were found only in coronary sinus flow, however not in coronary perfusion related to 100 g of left ventricular muscle mass. As regards indication for operation patients with aortic valve stenosis were differentiated according to transvalvular pressure differences. Pressure gradients of more than 90 mm Hg (n = 5) were associated with significant lowering of weight-related myocardial perfusion and oxygen consumption and high lactate production during stimulation. This evidence of myocardial ischaemia was also seen in 3 out of 11 patients with a pressure gradient between 51 and 90 mm Hg. The rest of the patients showed no significantly different measurements in comparison with the control group. Thus insufficient myocardial perfusion during exercise is likely in patients with transvalvular pressure differences of more than 90 mm/Hg and possible when the difference is more than 50 mm Hg.

Adult↗
PubMedDate not supplied

Biplane transesophageal color Doppler echocardiography for assessment of mitral valve area with mitral inflow jet widths.

Biplane transesophageal color Doppler echocardiography can image the mitral valve orifice in two orthogonal views. If the maximal stenotic jet width through the mitral valve obtained with the vertical transducer represents the major axis, the stenotic jet width dissected by the horizontal transducer should be the minor axis of the mitral orifice. Thus the mitral valve area can be calculated assuming an oval shape of mitral orifice. Nineteen patients with mitral stenosis were investigated. Maximal mitral stenotic jet width (JW1) was searched on a vertical plane and the jet width from the orthogonal view (JW2) was obtained on a horizontal plane. Mitral valve areas from the color Doppler jet widths were calculated by pi.JW1/2.JW2/2 and compared with those derived from Gorlin's formula. Adequate quality of echocardiographic images could be obtained in all patients for transesophageal color Doppler jet width measurements or Doppler pressure half-time determinations and in 16 of 19 patients for transthoracic planimetery of the mitral orifice at the parasternal short axis. Mitral valve areas derived from biplane transesophageal color Doppler imaging (1.31 +/- 0.53 cm2) were not different from those calculated according to Gorlin's formula from the catheterization data (1.25 +/- 0.50 cm2), those determined by transthoracic echocardiographic planimetery (1.38 +/- 0.5 cm2), or those calculated from the Doppler pressure half-time method (1.32 +/- 0.41 cm2) (difference not significant by analysis of variance). There was a very strong correlation between transesophageal echocardiographic mitral valve areas and those derived from catheterization data (r = 0.94; standard error of the estimate = 0.13 cm2). A similar correlation was obtained for the planimetric echocardiographic method (r = 0.94; standard error of the estimate = 0.14 cm2). A slightly less strong correlation was found between mitral valve areas derived from the Doppler pressure half-time method and those derived from Gorlin's formula (r = 0.83; standard error of the estimate = 0.24 cm2). The pressure half-time method accurately predicted the mitral valve area in most (15/19) patients, but it significantly (> 0.4 cm2) overestimated mitral valve area in two patients with aortic regurgitation and underestimated (< 0.4 cm2) mitral valve area in two patients with left ventricular hypertrophy. Determination of mitral valve area by color Doppler biplane transesophageal echocardiography is an alternative for accurate estimation of mitral valve area and may be most useful in intraoperative monitoring during surgical or balloon mitral commissurotomy or in the case of inadequate imaging quality of transthoracic echocardiography.

Adult↗