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Biomedical subjects

P De Haan

Publications and source records attributed to P De Haan.

14 recordsLinked to original sources
PubMed2000

Injury to the major airways during subtotal esophagectomy: incidence, management, and sequelae.

OBJECTIVE: The objective of this study was to gain insight into the incidence and sequelae of injury to the major airways during subtotal esophagectomy. METHODS: We performed an analysis of 383 consecutive patients undergoing this procedure between 1993 and 1999. Indications were adenocarcinoma (220), squamous cell carcinoma (121), and other (42). Transhiatal resection was done in 269 (70%) patients and transthoracic resection in 114 (30%). RESULTS: There were 4 men and 2 women (median age 57 years; range 45 to 68 years) with injury to the major airways, recognized during surgery in 5 patients and on the first postoperative day in the other. Five lesions occurred during transhiatal resection (5 of 269 = 1.8%) and 1 during transthoracic resection (1 of 114 = 0.8%; P =.67). The injury occurred proximal to the carina in 5 patients and in the left main bronchus in the other. All injuries could be closed primarily. The defect was covered with pericardium in 1 patient and with pleura in 2 patients. In all cases the gastric tube was placed over the defect. Pulmonary complications developed in 4 patients. Patients with tracheal injury required artificial ventilation for a longer period (median 6 days vs 1 day; P =.02) and stayed longer in the intensive care unit (median 11 vs 3 days; P <.01) than patients without such injury, although hospital time was not significantly prolonged (median 23 vs 16 days; P =.09). There was no associated mortality. CONCLUSION: Tracheobronchial injury is a rare complication of subtotal esophagectomy. It can be managed effectively by primary closure and apposition of vital tissue (gastric tube) to the defect. It is associated with pulmonary complications, leading to prolonged assisted ventilation and stay in the intensive care unit, but mortality is rare.

Adenocarcinoma↗
PubMed2000

Prevention of paraplegia in pigs by selective segmental artery perfusion during aortic cross-clamping.

PURPOSE: During thoracoabdominal aortic aneurysm repair, a prolonged interruption of the spinal cord blood supply can result in irreversible spinal cord damage. The aim of this study was to investigate whether selective segmental artery perfusion during aortic clamping could prevent paraplegia in pigs. METHODS: Specially designed segmental artery perfusion catheters, which could be attached to an extracorporeal bypass graft system, were used. In experiment I (n = 10), it was assessed whether selective segmental artery perfusion could reverse electrophysiologic evidence of spinal cord ischemia and maintain transcranial motor evoked potentials (tc-MEPs) during 60 minutes of aortic cross-clamping. The abdominal aorta, containing critical segmental arteries, was bypassed through use of an aortoaortic bypass graft system. After the disappearance of tc-MEPs, an aortotomy was followed by selective segmental artery perfusion. In experiment II (n = 10), the aim was to determine whether selective segmental artery perfusion could prevent paraplegia. In five animals (group A), aortic cross-clamping was followed by selective segmental artery perfusion; five control animals (group B) underwent segmental artery blockade only. Postoperative hind limb function and spinal cord histopathology were evaluated on the third postoperative day. RESULTS: In experiment I, tc-MEPs disappeared within 3.7 +/- 3.7 minutes after cross-clamping and returned in all animals in 8.5 +/- 5.3 minutes after selective perfusion. During the study period, tc-MEP amplitudes recovered to a median of 49% (range, 28%-113%) of baseline values. Total bypass graft flow was 880 +/- 294 mL/min, of which 184 +/- 54 mL/min was directed to the selective perfusion catheters. The flow in individual catheters was 52 +/- 13 mL/min. In experiment II, all perfused animals demonstrated normal hind limb function, whereas four of five control animals were paraplegic on day 3 (P =.04) In the perfused animals, histopathologic examination showed either no spinal cord damage or eosinophilic neurons only, whereas in paraplegic controls there was infarction in large areas of the cord (P <.0001). CONCLUSION: In pigs, selective segmental artery perfusion can provide sufficient spinal cord blood flow to prevent paraplegia resulting from 60 minutes of aortic clamping, as shown by clinical outcomes and histopathologic examination.

Animals↗
PubMed1999

The influence of regional spinal cord hypothermia on transcranial myogenic motor-evoked potential monitoring and the efficacy of spinal cord ischemia detection.

OBJECTIVE: Myogenic motor-evoked responses to transcranial electrical stimulation (transcranial myogenic motor-evoked potentials) can rapidly detect spinal cord ischemia during thoracoabdominal aortic aneurysm repair. Recent evidence suggests that regional spinal cord hypothermia increases spinal cord ischemia tolerance. We investigated the influence of subdural infusion cooling on transcranial myogenic motor-evoked potential characteristics and the time to detect spinal cord ischemia in 6 pigs. METHODS: Regional hypothermia was produced by subdural perfusion cooling. A laminectomy and incision of the dura were performed at L2 to advance 2 inflow catheters at L4 and L6, to cool the lumbar subdural space with saline solution. Two temperature probes were advanced at L3 and L5, and 1 cerebrospinal fluid pressure line was advanced at L4. Spontaneous cerebrospinal fluid outflow was allowed. Spinal cord ischemia was produced by clamping a set of critical lumbar arteries, previously identified by transcranial myogenic motor-evoked potentials and lumbar artery clamping. The time between the onset of ischemia and detection with transcranial myogenic motor-evoked potentials (amplitude < 25%) was determined at cerebrospinal fluid temperatures of 37 degrees C and 28 degrees C. Thereafter, the influence of progressive cerebrospinal fluid cooling on transcranial myogenic motor-evoked potential amplitude and latency was determined. RESULTS: The time necessary to produce ischemic transcranial myogenic motor-evoked potentials, after the clamping of critical lumbar arteries, was not affected at moderate subdural hypothermia (3.8 +/- 0.9 min) compared with subdural normothermia (3.2 +/- 0.5 min; P =.6). Thereafter, progressive cooling resulted in a transcranial myogenic motor-evoked potential amplitude increase at 28 degrees C to 30 degrees C and was followed by a progressive decrease. Response amplitudes decreased below 25% at 14.0 degrees C +/- 1.1 degrees C. The influence of cerebrospinal fluid temperature on transcranial myogenic motor-evoked potential amplitude was best represented by a quadratic regression curve with a maximum at 29.6 degrees C. In contrast, transcranial myogenic motor-evoked potential latencies increased linearly with decreasing subdural temperatures. CONCLUSIONS: Detection of spinal cord ischemia with transcranial myogenic motor-evoked potentials is not delayed at moderate subdural hypothermia in pigs. At a cerebrospinal fluid temperature of 28 degrees C, transcranial myogenic motor-evoked potential amplitudes are increased. Further cerebrospinal fluid temperature decreases result in progressive amplitude decreases and latency increases.

Animals↗
PubMed1999

Comparison of transcranial motor evoked potentials and somatosensory evoked potentials during thoracoabdominal aortic aneurysm repair.

OBJECTIVE: To compare transcranial motor evoked potentials (tc-MEPs) and somatosensory evoked potentials (SSEPs) as indicators of spinal cord function during thoracoabdominal aortic aneurysm repair. SUMMARY BACKGROUND DATA: Somatosensory evoked potentials reflect conduction in dorsal columns. tc-MEPs represent anterior horn motor neuron function. This is the first study to compare the techniques directly during thoracoabdominal aortic aneurysm repair. METHODS: In 38 patients, thoracoabdominal aortic aneurysm repair (type I, n = 10, type II, n = 14, type III, n = 6, type IV, n = 8) was performed using left heart bypass and segmental artery reimplantation. tc-MEP amplitudes <25% and SSEP amplitudes <50% and/or latencies >110% were considered indicators of cord ischemia. The authors compared the response of both methods to interventions and correlated the responses at the end of surgery to neurologic outcomes. RESULTS: Ischemic tc-MEP changes occurred in 18/38 patients and could be restored by segmental artery reperfusion (n = 12) or by increasing blood pressure (n = 6). Significant SSEP changes accompanied these tc-MEP events in only 5/18 patients, with a delay of 2 to 34 minutes. SSEPs recovered in only two patients. In another 11 patients, SSEP amplitudes fell progressively to <50% of control without parallel tc-MEP changes or association with cross-clamp events or pressure decreases. At the end of the procedure, tc-MEP amplitudes were 84 +/- 46% of control. In contrast, SSEP amplitudes were <50% of control in 15 patients (39%). No paraplegia occurred. CONCLUSION: In all patients, tc-MEP events could be corrected by applying protective strategies. No patient awoke paraplegic. SSEPs showed delayed ischemia detection and a high rate of false-positive results.

Adult↗
PubMed1993

Increased adherence to keratinocytes of peripheral blood mononuclear leucocytes of a patient with drug-induced erythema multiforme.

The pathogenetic mechanisms involved in the development of drug-induced erythema multiforme (EM) are still largely unknown. The observation that epidermal keratinocytes (KC) in EM express intercellular adhesion molecule-1 (ICAM-1) points to a putative role for T-cell/KC adhesion in the pathogenesis of EM. In this study, the binding of peripheral blood mononuclear leucocytes (PBML) from a patient with carbamazepine-induced EM and of normal control PBML to autologous and heterologous KC was investigated, using two different binding assays. Patient PBML obtained at the time of disease (t0) showed an increased binding to ICAM-1-positive heterologous KC, which could be inhibited completely by anti-LFA-1. Adhesion of patient PBML-t0 to autologous KC, and to carbamazepine-pretreated heterologous KC in sections of skin biopsies, was also increased, but was found to be only partially LFA-1-dependent. These findings support the view that PBML/KC adherence plays an important role in the pathogenesis of this drug-induced EM.

Adult↗
PubMed1991

The nonstructural protein (NSs) encoded by the ambisense S RNA segment of tomato spotted wilt virus is associated with fibrous structures in infected plant cells.

The open reading frame located in the viral strand of the ambisense S RNA of tomato spotted wilt virus (TSWV), was cloned into transfer vector pAc33DZ1 and inserted downstream of the polyhedrin promoter in the Autographa californica nuclear polyhedrosis virus genome. Recombinant baculoviruses were obtained that showed a high-level expression of a 52.4-kDa protein corresponding to the inserted TSWV gene. The viral protein thus produced was purified and injected into rabbits to raise antibodies. Western immunoblot analyses of extracts from TSWV-infected plants demonstrated that the 52.4-kDa TSWV-specific polypeptide represents a nonstructural protein (denoted NSs), being absent in purified virus particles. Immunogold labeling of tissue sections of TSWV-infected Nicotiana rustica plants showed that this protein was, depending on the virus isolate, either found dispersed throughout the cytoplasm or associated with fibers which appeared as elongated flexible filaments or paracrystalline rods.

Animals↗
PubMed1990

Spectophotometric quantification of cell-cell adherence by an enzyme-linked immuno-cell adhesion assay.

In the present study a spectophotometric method was developed to determine the number of T cells binding to human epidermal keratinocytes (KC). In this cell adhesion assay the adherent T cells were detected with a cell-specific monoclonal antibody conjugated to horseradish peroxidase and the coloured substrate quantified in an ELISA reader at 492 nm. A correlation was demonstrated between the number of T cells and the extinction values measured. The enzyme-linked immuno-cell adhesion assay (ELICAA) was used to quantify KC/T lymphocyte adherence in a series of experiments designed to evaluate its reliability and reproducibility. Compared with the 51Cr-labelled adherence assay, the ELICAA was a safe, rapid and accurate method avoiding the use of radioactive material.

Antibodies, Monoclonal↗
PubMed1989

Molecular cloning and terminal sequence determination of the S and M RNAs of tomato spotted wilt virus.

Complementary DNA to the genomic RNA of tomato spotted wilt virus (TSWV) was synthesized and cloned in either pUC19 or lambda gt10. Restriction endonuclease maps were constructed from cDNA clones specific for the S and the M RNA segments, extending 3.0 and 5.4 kbp respectively. The nucleotide sequences of the 3' and 5' termini of both RNA molecules were determined. The S and M RNAs contain inverted complementary repeats at their termini, probably involved in RNA replication and in the formation of circular nucleocapsids in virions. The terminal structures of the TSWV genome resemble, in these aspects, those of the Bunyaviridae.

Base Sequence↗
PubMed1989

Effects of sustained-release chlorhexidine acetate on the human dental plaque flora.

The aim of this study was to determine the effect on the human dental plaque flora of a varnish containing chlorhexidine diacetate. The in vitro release of chlorhexidine acetate from the varnish preparation was relatively fast on the first day, followed by a substantial decline in the subsequent three days. In a clinical experiment, 26 volunteers were randomly distributed over four experimental groups. After a dental prophylaxis, the subjects were treated with a single application of a placebo varnish (group I), a fluoride varnish (group II), a chlorhexidine varnish (group III), or a fluoride-plus-chlorhexidine varnish (group IV). Saliva and pooled plaque samples from approximal surfaces were taken before (baseline) and one, two, three, four, and six weeks after the treatments. No suppression was found of total cultivable flora or S. sanguis after the experimental treatments. Application of the fluoride varnish did not suppress the A. viscosus/naeslundii or S. mutans levels in the dental plaque. Chlorhexidine suppressed A. viscosus/naeslundii until two weeks after the treatment. S. mutans was significantly suppressed until four weeks after a single chlorhexidine application. While in some subjects S. mutans was effectively suppressed over the whole experimental period, in others S. mutans recovered quickly. In five subjects in whom S. mutans recovered quickly, the dentition was treated twice with chlorhexidine varnish, with an interval of one week between the treatments. After two chlorhexidine treatments, S. mutans in saliva and on the teeth was suppressed more strongly than after a single treatment. However, the second chlorhexidine treatment could not prevent the return of S. mutans in the approximal areas to its original level.

Actinomyces↗
PubMed1986

Detection of specific anti-hapten antibody-producing hybridoma cells in tissue sections of spleen and liver by hapten-enzyme conjugates using an immunoenzyme approach.

A method is presented for the detection of hybridoma cell growth in vivo by making use of the specific antigen (hapten) recognition properties of the produced monoclonal antibodies. Horseradish peroxidase (HRP)-labeled antigen was used for demonstration of intracellular specific antibodies in hybridoma cells. It appeared that intravenously injected anti-penicilloyl-producing hybridoma cells developed mainly in the red pulp of the spleen; to a lesser extent they were found in the liver.

Animals↗
PubMed1984

Oral controlled release dosage forms. A review.

When a drug meets the criteria which make incorporation into a controlled release dosage form rational, a proper dosage form has to be selected. Oral controlled release products, available on the Dutch market, are referred to in discussing the various methods used to control drug release by galenical means in order to achieve a prolonged therapeutic effect. The effects of some physiological variables of the alimentary tract on drug delivery from the various dosage forms, especially with regard to formulation and design, are reviewed.

Administration, Oral↗
PubMed1984

Double immunocytochemical staining in the study of antibody-producing cells in vivo. Simultaneous detection of anti-hapten and anti-carrier antibody-producing cells in lymphoid tissue.

Mice were injected intravenously with 2 mg of a bovine gamma globulin-penicilloyl (BGG-Pen) conjugate. Cells producing specific antibodies against the protein carrier bovine gamma globulin (BGG) and cells producing specific antibodies against the hapten penicilloyl (Pen) could be distinguished simultaneously in the same spleen section using a combined peroxidase (HRP) and alkaline phosphatase (AP) immunocytochemical technique. AP-BGG conjugate was used for detection of anti-BGG-producing cells and HRP-human serum albumin (HSA)-Pen conjugate, prepared by coupling penicillin to HRP-HSA conjugate, was used for detection of anti-Pen-producing cells in the same spleen section. After performing both HRP and AP cytochemistry, cells with a blue-stained cytoplasm represent anti-BGG-producing cells and cells with a red-stained cytoplasm represent anti-Pen-producing cells.

Animals↗
PubMed1982

Studies on different dissolution models. IV. Erosion of tablets.

A comparative study of the action of erosion on non disintegrating theophylline tablets was performed in the three USP XX dissolution models, the rotating basket, the paddle and the modified disintegration apparatus, as well as in a new (sandwich) model. The results show erosion to be dependent on the mechanical strength of the tablets and to be promoted by the phenomenon of softening of the tablets during the process of dissolution. A considerable and moderate erosion was found for 'soft' tablets in the rotating basket and disintegration apparatus, respectively, whereas no or only slight erosion was observed in the paddle and sandwich models. The phenomenon of dissolution intensified erosion and erosion intensified dissolution is shown to affect the description of the release profiles. The dissolution profiles of the 'hard' tablets in the models preferred to be described by the square root equation, whereas the profiles of the 'soft' tablets in the case of erosion showed a tendency to a better fit with the cube root of mass versus time relation.

Kinetics↗