Biomedical subjects

J M Hartog

Publications and source records attributed to J M Hartog.

At least 19 recordsLinked to original sources

PubMed1999

Maxillary reconstruction: functional and aesthetic considerations.

Maxillary reconstruction is a challenging endeavor in functional and aesthetic restoration. Given its central location in the midface and its contributions to the key midfacial elements--the orbits, the zygomaticomaxillary complex, the nasal unit, and the stomatognathic complex--the maxilla functions as the keystone of the midface and unifies these elements into a functional and aesthetic unit. Maxillary defects are inherently complex because they generally involve more than one midfacial component. In addition, most maxillary defects are composite in nature, and they often require skin coverage, bony support, and mucosal lining for reconstruction. In the reconstruction of maxillary defects secondary to trauma, ablative tumor surgery, or congenital deformities, the following goals must be met: (1) obliteration of the defect; (2) restoration of essential functions of the midface, such as mastication and speech; (3) provision for adequate structural support to each of the midfacial units; and (4) aesthetic reconstruction of the external features. This review will discuss the pertinent anatomic considerations, the historical approaches to maxillary reconstruction, and the merits of the techniques in use today, with an emphasis on state-of-the-art reconstruction and dental rehabilitation of extensive maxillary defects.

Esthetics↗

PubMed1993

Closure of a coronary cameral fistula following endomyocardial biopsies in a cardiac transplant patient with a detachable balloon.

Endomyocardial biopsy is the reference standard for the diagnosis of cardiac allograft rejection and is performed frequently in cardiac transplant patients. Biopsies are taken percutaneously via the right internal jugular or femoral vein. Fistulas from coronary arteries into the right ventricle following endomyocardial biopsies are a relatively frequent finding. Most of these fistulas are small angiographically, haemodynamically insignificant, and tend to disappear. We report a case of a haemodynamic significant coronary fistula, closed by a percutaneously introduced detachable balloon.

Biopsy↗

PubMed1993

Development and regression of atherosclerosis in pigs. Effects of n-3 fatty acids, their incorporation into plasma and aortic plaque lipids, and granulocyte function.

Fifty-one pigs were fed a low-cholesterol basal diet, to which either 10% (by weight) of lard fat (group INORM, n = 7), 2% cholesterol plus 8% lard fat (group II, n = 33), or 2% cholesterol plus 4% lard fat plus 4% fish oil (group IIIPREV, n = 11) was added. In all pigs, the left anterior descending coronary artery and the abdominal aorta were denuded at 1 month. In the first 24 hours thereafter, three animals in group II and two in group IIIPREV died suddenly. After 3 months, 0.5% bile acids was added to the diet in groups II and IIIPREV. After 8 months the degree of atherosclerosis was evaluated in groups INORM and IIIPREV and in 14 animals from group II (IIIND). At 4 months, one animal from Group II died of pneumonia. For the next 4 months (postinduction period), the remaining 15 animals from group II received the basal diet, to which either 10% lard fat (group IILF, n = 6) or 5% lard fat plus 5% fish oil (group IIFO, n = 9) was added. The hypercholesterolemic diet increased plasma cholesterol from 2 to 9-12 mM after 8 months. Fish oil had no major effects on plasma lipids during both induction and postinduction. Superoxide production by granulocytes in response to the membrane receptor-dependent N-formyl-methionyl-leucyl-phenylalanine (fMLP) gave a higher response in group IIIND than in group INORM. In group IIIPREV, the response to phorbol myristate acetate (PMA) and fMLP was lowered, while in groups IIFO and IILF the responses to PMA and fMLP were not affected. The response to serum-treated zymosan was similar in all groups. Abrasion caused increases in free cholesterol (40%) and phospholipids (46%) in the abdominal aortas of group INORM animals. Hypercholesterolemia increased both free and esterified cholesterol in the entire aorta. Fish oil prevented accumulation of free cholesterol in the nonabraded ascending aorta during induction and further accumulation of free cholesterol and phospholipids in the abdominal aorta during postinduction. In the nonabraded ascending aorta, triglycerides were significantly (almost five times) lower in group IIFO than in group IILF. During both induction and postinduction, a large incorporation of n-3 polyunsaturated fatty acids (up to 20%) occurred in plasma and aortic cholesterol esters and phospholipids of groups IIFO and IIIPREV.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

Failure of diltiazem to suppress cholesterol-induced atherogenesis of endothelium-denudated arteries in pigs.

To investigate the effect of diltiazem on the development of atherosclerosis, 15 pigs were fed a fat-poor basal diet to which 8% (w/w) lard fat and 2% (w/w) cholesterol were added for 8 months. To enhance the formation of atherosclerotic plaques endothelium of the aorta and the left anterior descending coronary artery was removed after 1 month and 0.5% (w/w) bile acids were added to the diet after 3 months. Seven animals served as control, while 8 animals also received diltiazem (the first 2 months 10 mg/kg twice daily and during the remainder of the dietary period 5 mg/kg twice daily). The diet-induced increases in plasma level of total cholesterol were not affected by diltiazem. Triglyceride levels did not change in the control group but decreased significantly in the diltiazem-treated animals. Collagen-induced (1 microgram/ml) platelet aggregation was increased by diltiazem. The sum of free and esterified cholesterol was increased in the lesions of the aortic wall in the diltiazem-treated animals (9.8 +/- 1.3 micrograms/g wet weight vs. 6.3 +/- 1.0 mumol/g wet weight in the untreated animals), but coverage of the aorta with sudanophilic lesions was similar for both groups (40 +/- 4% for the treated and 34 +/- 9% for the control animals). Narrowing of the previously abraded coronary arteries was similar for the diltiazem-treated (median 7.1%, ranges 2.6-29.0%) and the control group (median 10.0%, ranges 2.3-24.1%). It is concluded that the dose range of diltiazem of 5-10 mg/kg twice daily, which is close to that used in the clinical setting, had no effect on the experimentally induced atherogenesis in pigs.

Animals↗

PubMed1990

Reconstruction of the temporomandibular joint with cryopreserved cartilage and freeze-dried dura: a preliminary report.

A technique for total reconstruction of the temporomandibular joint using cryopreserved cartilage and freeze-dried dura is described. The rationale, indications, and surgical technique are discussed. The technique has been used in nine joints in seven patients, followed between 3 and 27 months. There was one total failure of the graft, with the remainder maintaining good, asymptomatic joint function.

Cartilage, Articular↗

PubMed1990

Comparison of methods to assess neurosensory alterations following orthognathic surgery.

Orthognathic surgery may damage branches of the trigeminal nerve, resulting in postoperative neurosensory disturbances. Alterations may be due to surgical edema, stretching, or direct trauma to the nerve. Lack of a standard and objective method of assessment hinders efforts to study and/or reduce the incidence of neurosensory disturbances. This study compared three methods of assessing neurosensory disturbances in patients who underwent bilateral mandibular ramus sagittal split osteotomies. Forty patients (26 female, 14 male) ranging in age from 23 to 47 years participated in the study. All of the patients had bilateral mandibular ramus sagittal split osteotomies and were stabilized with rigid skeletal fixation. Neurosensory testing was performed prior to surgery, and at 2 weeks, 1 month, 3 months, 6 months, and 1 year following surgery. Methods of assessment included two-point discrimination, threshold to electrical stimulation, and somatosensory evoked potentials. Threshold to electrical stimulation and two-point discrimination were obtained by the two-alternate forced choice technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

Effects of diets supplemented with lard fat or mackerel oil on plasma lipoprotein lipid concentrations and lipoprotein lipase activities in domestic swine.

Levels of plasma lipoproteins and lipoprotein lipase activities in post-heparin serum were measured in 24-h fasted pigs which were fed a diet containing either 21 energy % mackerel oil or 21 energy % lard fat for 8 weeks. Lipoprotein fractionation was performed separately by density gradient ultracentrifugation and agarose gel chromatography. After 8 weeks levels of plasma triacylglycerol (-62%) and cholesterol (-55%) were lower in the mackerel oil than in the lard fat-fed animals. The triacylglycerol decline was exclusively due to the VLDL fraction, while cholesterol was reduced in all lipoprotein fractions (VLDL, IDL, LDL and HDL). Lipoprotein lipase activity in post-heparin serum, taken 6 h after a meal, was 31% decreased in mackerel oil-fed animals. The results support the hypothesis that regular intake of fish oil reduces VLDL secretion.

Animals↗

PubMed1989

Does platelet aggregation play a role in the reduction in localized intimal proliferation in normolipidemic pigs with fixed coronary artery stenosis fed dietary fish oil?

In order to investigate the effect of fish oil on intimal proliferation of coronary arteries with a fixed stenosis normolipidemic piglets received a basic diet to which either 9% (w/w) lard (L, n = 8) or 4.5% (w/w) lard and 4.5% (w/w) mackerel oil (ML, n = 8) was added for 4 months. Stenosis was applied by implanting a 4.0 X 2.0 mm (i.d.) Teflon constrictor around the left anterior descending coronary artery (LADCA) (o.d. 2.7 +/- 0.1 mm). During the dietary period ADP-induced platelet aggregation in whole blood was higher in L than in ML. Partial replacement of 20:4 n - 6 by 20:5 n - 3 fatty acids in the platelet membranes of ML may have altered platelet aggregation by changes in eicosanoid synthesis. The plasma cholesterol and triglyceride levels did not change in L, but decreased in ML. At the end of the 4-month dietary period the animals were again anesthetized and regional myocardial perfusion (radioactive labelled microspheres) and systolic segment length shortening (SLS) were measured while the hearts were paced at 160 pulses/min. Perfusion and SLS of non-LADCA nourished segment were similar for L and ML. However, transmural flow to the LADCA perfused myocardium was impaired in both groups, but the deficiency in endocardial perfusion was considerably larger in L than in ML, resulting in a larger loss of SLS in the former. Remote (2-3 cm from the site of the constrictor) luminal encroachment was minimal (less than 2%) in both groups, but at the site of the constrictor there was significant encroachment in both groups which was higher in L (62 +/- 7%) than in ML (11 +/- 4%). It is thought that in these normolipidemic pigs the reduction in platelet aggregation may play a role in the smaller intimal proliferation of the fish oil-fed animals.

Animals↗

PubMed1989

Intimal proliferation in coronary arteries of normolipidaemic pigs with a fixed stenosis: the effects of fish oil.

In order to investigate the effect of fish oil on intimal proliferation of coronary arteries with a fixed stenosis, piglets were fed a diet to which either 9% (w/w) lard fat (L, n = 8) or 4.5% (w/w) lard fat and 4.5% (w/w) mackerel oil (ML, n = 8) was added for 4 months. The stenosis was applied by implanting a Teflon constrictor around the left anterior descending coronary artery (LADCA) after the animals had been on their diet for two months. Levels of plasma cholesterol and triglycerides did not change in L, but decreased in ML, while ADP-induced platelet aggregation in whole blood was higher in L than in ML. At the end of the dietary period the animals were anaesthetized and myocardial perfusion and systolic segment length shortening (SLS) were measured while the hearts were paced at 160 pulses min-1. Transmural blood flow to the non-LADCA nourished zones were normal and similar for L and ML, but impaired in the LADCA-perfused myocardium. In particular the subendocardial layers of L were hypoperfused resulting in a larger loss of SLS in L than in ML. A significantly higher encroachment due to intimal proliferation was found in L (62 +/- 7%) than in ML (11 +/- 4%) at the site of the constrictor while this was less than 2% adjacent to the constrictor. We conclude that the presence of the constrictor causes intimal proliferation and that the fish oil-induced changes in platelet aggregation may play a role in determining the extent to which this occurs.

Animals↗

PubMed1989

Mackerel oil and atherosclerosis in pigs.

In 35 pigs atherosclerosis was induced by balloon abrasion and a diet containing 2% (w/w) cholesterol and 7% (w/w) lard fat. After 4 months of induction nine animals were killed (I) for analysis of the extent of atherosclerosis, while the diet of the other 26 pigs was changed to a low cholesterol diet containing either 9% (w/w) lard fat (L), 9% (w/w) fish oil (F) or 4.5% (w/w) lard fat and 4.5% (w/w) fish oil (LF). This diet was continued for 3 months to induce regression of atherosclerosis. The cholesterol-rich diet increased plasma total cholesterol, but did not affect plasma triglycerides. Low-cholesterol feeding decreased plasma total cholesterol in all three groups, but triglycerides only in LF and F. Lipid infiltration of the aortic wall was similar in I, L, LF and F. In the denudated coronary arteries of I mean luminal encroachment was 11 +/- 2%. This was similar in L (13 +/- 4%) but significantly lower (P less than 0.05) in LF (6 +/- 2%) and in F (3 +/- 1%). In the non-abraded coronary arteries of I mean luminal encroachment was 1.3 +/- 0.3%. For F and LF similar values were found, but in L there was an increase to 11 +/- 3% during low-cholesterol feeding. ADP-induced platelet aggregation was lower in LF and F than in L. Thromboxane A2 production was only reduced in F, while the production of the weak thromboxane A3 agonist was larger in F than in LF. It is concluded that fish oil retards the progression of and causes regression of coronary atherosclerosis.

Animals↗

PubMed1988

Lipid peroxidation in normoxic and ischaemic-reperfused hearts of fish oil and lard fat fed pigs.

The in situ and in vitro rate of lipid peroxidation of hearts were determined in two groups of pigs which had been fed diets which differed only in fatty acid composition for 8 weeks. During the dietary period venous plasma levels of malondialdehyde and lipofuscin were not higher in pigs receiving the highly unsaturated fatty acid-containing mackerel oil than those receiving lard fat. Malondialdehyde was produced in the coronary system of the mackerel oil fed animals. After the heart was subjected to a sequence of short periods of ischaemia (5 min) and reperfusion (10 min), myocardial malondialdehyde production in the mackerel oil fed pigs did not increase. Contribution of prostaglandin synthesis products to myocardial malondialdehyde formation is probably of minor importance. Recovery of regional heart function after the ischaemic periods was similar for both dietary groups. In the phospholipids of sarcolemmal preparations isolated from the left ventricle of mackerel oil fed animals 18:2 n-6 and 20:4 n-6 were partially replaced by 20:5 n-3 and 22:6 n-3. Ischaemia-reperfusion did not alter sarcolemmal fatty acid composition and Ca2+ pumping ATPase activity. Sarcolemmal membrane from mackerel oil fed pigs exposed in vitro to a free radical generating system showed a higher malondialdehyde production than that from lard fat fed pigs. Thus, in spite of the increased susceptibility of heart membranes to free radical generated peroxidation in mackerel oil fed animals, recovery of left ventricular function was similar following multiple short-term periods of ischaemia.

Animals↗

PubMed1988

Dietary fish oil reduces intimal proliferation of the coronary artery caused by implantation of a constrictor in pigs.

Piglets received a basal diet to which either lard fat (L) or a mixture of lard fat and mackerel oil (ML) was added. After 2 months a constrictor was placed around the left descending coronary artery (LADCA) and the dietary regimen continued for 2 more months. During the dietary period plasma thromboxane B2 levels, thromboxane B2/6-keto-PGF1 alpha ratio, platelet membrane 20:4 n-6 content and ADP-induced platelet aggregation were all lower in ML than in L. Morphological examination at the site of the LADCA stenosis showed a higher encroachment due to intimal proliferation in L. It is postulated that alterations in eicosanoid synthesis indirectly affected the rate of intimal proliferation.

6-Ketoprostaglandin F1 alpha↗

PubMed1987

Dietary fatty acids and myocardial function.

It is widely recognized that dietary polyunsaturated fatty acids (PUFA's) and cholesterol can profoundly influence the development of atherosclerotic plaques in coronary vessels, which may lead to myocardial infarction. The possibility that dietary fatty acids may also directly influence cardiac function has received less attention. We therefore reviewed the evidence of the effects of dietary fatty acids, in particular n-3 and n-6 PUFA's, on myocardial phospholipid fatty acid composition and cardiovascular performance. Heart organelles appear to incorporate uncommon fatty acids like 22:1 and trans- 18:1. Diets enriched with 22:1 induce myocardial lipidosis. N-9, n-6 and n-3 families compete among membrane C20 and C22 acids. Several studies have dealt with the relation between diet-induced changes of cardiac membrane (sarcolemma, sarcoplasmic reticulum and mitochondria) phospholipids and membrane function. In view of the variety of diets used and of the membrane functions studied, the results do not permit equivocal interpretation. Several investigators have reported an altered stress response of the heart due to a change of PUFA's in the diet. In rats fed with a low 18:2n-6/18:3n-3 ratio combined with relatively low amounts of saturated fatty acids, a high incidence of myocardial lesions has been observed. Pigs are less sensitive but more susceptible to the development of vitamin E deficiency, when the dietary PUFA content is high. Increased contractility and coronary flow rate have been reported for Langendorff-perfused hearts of rats fed 18:2n-6-rich diets. The effects on coronary flow rate are possibly related to alterations in eicosanoid synthesis, which may also contribute to the reduction by n-6 or n-3 PUFA's in infarct size, magnitude of recovery of function and suppression of reperfusion arrhythmias following release of a coronary artery ligation. On the other hand, increased peroxidation of membrane lipids, due to their high content of n-3 PUFA, may be deleterious.

Animals↗

PubMed1987

The effects of dietary mackerel oil on the recovery of cardiac function after acute ischaemic events in the pig.

To investigate the effects of fish oil nutrition on cardiac haemodynamics and the biochemical response to ischaemia-reperfusion, young pigs (5 weeks old) were fed a 9% lard fat diet or a mixed diet of 4.5% mackerel oil and 4.5% lard fat for 16 weeks. In the mackerel oil fed pigs plasma cholesterol and triglyceride levels decreased by 22% and 58% (both p less than 0.05), respectively, while levels in the animals which received only lard fat did not change. The n-6 fatty acids present in cardiac and platelet membrane phospholipids underwent a partial replacement by n-3 fatty acids in the mackerel oil fed pigs. Under anaesthesia, multiple coronary artery occlusions (5 min) were interrupted by 10 min of reperfusion. The extent of recovery of cardiac function and reduction of adenine nucleotide levels were similar for both dietary groups. The incidence of reperfusion arrhythmias was significantly lower and the reactive hyperaemic responses were of longer duration in the mackerel oil fed animals. These effects cannot be explained by diet-induced alterations in thromboxane B2/6-keto-PGF1 alpha ratio, although a marked reduction in absolute levels of both prostaglandins was seen in the mackerel oil fed pigs (p less than 0.05). In conclusion, dietary fish oil caused changes in membrane fatty acid composition and plasma prostaglandin levels, although these did not affect alterations of cardiac performance during and after short periods of ischaemia.

Animals↗

PubMed1987

Coralline porous hydroxylapatite as a bone graft substitute in orthognathic surgery.

This prospective study was undertaken to evaluate the use of coralline porous hydroxylapatite as a bone graft substitute in orthognathic surgery. Ninety-two consecutive patients received a total of 355 block implants to the maxilla (294), mandible (41), and midface (20). There were 202 implants positioned directly adjacent to the maxillary sinus. Complications were minimal, the most common being exposure of the implant to the oral or nasal cavity. Histologic evaluation of implants that were biopsied in nine patients, four to 16 months postsurgery, revealed connective tissue ingrowth throughout the implants with approximately one-third being bone of variable maturity and two-thirds being soft tissue.

Adolescent↗

PubMed1987

Comparison of mackerel-oil and lard-fat enriched diets on plasma lipids, cardiac membrane phospholipids, cardiovascular performance, and morphology in young pigs.

Purified mackerel-oil extract or lard fat (9.1% wt/wt) was added to a basal diet of young pigs for 8 wk. Effects on plasma lipids, glucose and insulin, cardiac membrane phospholipids, cardiovascular performance, and morphology were studied. A time-dependent reduction of plasma triglyceride (62%), total cholesterol (41%), and HDL cholesterol (47%) was found in the mackerel-oil-fed pigs. The postprandial glucose and insulin response may indicate a mackerel-oil-induced resistance of insulin receptors. Although the polyunsaturated fatty acid composition of cardiac sarcolemma widely differed between the two groups, all determined indices of heart function were equal. It is concluded that consumption of a fish-oil diet with a low content of monoenes and supplemented with antioxidants reduces plasma lipid levels without producing pathological side effects.

Animals↗

PubMed1987

Dietary mackerel oil in pigs: effect on plasma lipids, cardiac sarcolemmal phospholipids and cardiovascular parameters.

The influence of substitution of eicosapentanoic acid to the diet has been investigated in juvenile domestic pigs (7-8 kg) fed either a mixture of 4.5% (wt/wt) mackerel oil and 4.5% (wt/wt) lard fat (n = 12, ML group) or a 9% (wt/wt) lard fat (n = 12, L group) diet for 16 wk. Plasma triglyceride and total cholesterol did not change in L, but had decreased in ML to 51 +/- 8 and 81 +/- 8% of the initial values, respectively, at the end of this period; the largest decreases already occurred during the first 8 wk. HDL cholesterol of both L and ML were not affected. After 16 wk, postprandial responses of plasma triglyceride, total cholesterol and glucose and insulin, determined at hourly intervals during the first 8 h postfeeding, did not show any differences for the two dietary groups. In spite of a marked replacement of n-6 fatty acids by n-3 fatty acids in cardiac sarcolemmal membranes in ML, there were no major differences in cardiovascular performance (myocardial contractility, pre- and afterload, cardiac output and myocardial work) between L and ML, when measured under baseline conditions and after the heart was stressed by atrial pacing (heart rate: 160 beats/min). In conclusion, feeding moderate amounts of mackerel oil [0.3 g 20:5 n-3/(kg body weight.d)] to pigs during 16 wk produces decreases of the plasma levels of total cholesterol and triglyceride, but does not affect plasma HDL cholesterol and routine cardiovascular parameters.

Animals↗

PubMed1987

Systemic haemodynamic actions of pimobendan (UD-CG 115 BS) and its O-demethylmetabolite UD-CG 212 Cl in the conscious pig.

The cardiovascular effects of the pyridazinone-derivatives pimobendan and its O-demethylmetabolite UD-CG 212 Cl (2-(4-hydroxy-phenyl)-5-(5-methyl-3-oxo-4,5-dihydro-2H-6-pyridazinyl) benzimidazole HCl) were studied in conscious pigs, employing consecutive intravenous 10 min infusions of 10, 25, 50 and 100 micrograms kg-1 min-1 and 2, 4 and 8 micrograms kg-1 min-1 respectively. Pimobendan caused dose-dependent increases in LVdP/dtmax (up to 115%) and heart rate (up to 30%), while cardiac output was slightly elevated (up to 15%) and stroke volume decreased by 12%. Left ventricular end-diastolic pressure decreased in a dose-related manner from 8.7 +/- 1.0 mmHg to 2.7 +/- 1.7 mmHg. Mean arterial blood pressure was not significantly affected because systemic vascular resistance decreased dose-dependently up to 15%. After beta-adrenoceptor blockade, the pimobendan-induced increases in heart rate and cardiac output were attenuated and the increase in LVdP/dtmax almost abolished. The responses of left ventricular end-diastolic and mean arterial blood pressure, systemic vascular resistance and stroke volume were not modified. UD-CG 212 Cl caused dose-related increases in LVdP/dtmax (up to 100%) and heart rate (up to 25%). Cardiac output was minimally elevated (up to 8%) as stroke volume decreased dose-dependently up to 15%. As systemic vascular resistance decreased up to 12%, mean arterial blood pressure was slightly reduced (5%). Left ventricular end-diastolic blood pressure decreased dose-dependently from 9.0 +/- 0.8 mmHg to 3.8 +/- 1.3 mmHg. After beta-adrenoceptor blockade, the UD-CG 212 Cl-induced increases in heart rate and LVdP/dtmax were attenuated and almost abolished and amounted up to 15% and 20%, respectively. The responses of the other systemic haemodynamic parameters were not significantly modified. We conclude that pimobendan and UD-CG 212 Cl are compounds with marked positive inotropic and venodilator properties in the conscious pig. The attenuation of the inotropic effects by pretreatment with propranolol strongly suggests that, in the conscious pig, the beta-adrenergic system is significantly involved in the positive inotropic actions. The lack of effect of beta-adrenoceptor blockade on the vasodilator responses to both compounds suggest a mechanism not related to beta-adrenergic activity.

Animals↗