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Biomedical subjects

D Lang

Publications and source records attributed to D Lang.

At least 145 records · Page 8Linked to original sources
PubMed1992

The management of orbital roof fractures.

The nature and aetiology of orbital roof fractures is discussed and a strategy for their successful management outlined with reference to five clinical cases. Early recognition and treatment of these fractures reduces the high incidence of intra-cranial and ocular complications and the importance of a combined approach involving maxillofacial surgeons, neurosurgeons and ophthalmologists is emphasised. A coronal flap together with frontal craniotomy is recommended for surgical access to the orbital roof and overlying dura. When reconstruction is indicated, autogenous bone harvested from the inner table of the calvarium provides an ideal graft material.

Adult↗
PubMed1992

Atrial automatic tachycardia in infancy and childhood.

Twenty-one cases (13 male, eight female) of atrial automatic tachycardia (AAT) assessed by standard and Holter-ECG in otherwise healthy infants and children have been documented. AAT was incessant in 12 patients, repetitive in seven, and of undetermined type in the remaining two. The frontal P wave axis suggested an ectopic focus in the high right atrium or right atrial appendage in 13 patients, in the low right atrium in one patient, and in the left atrium in seven patients. Thirteen out of 14 patients with the incessant or undetermined type of AAT were symptomatic, in contrast to only two of seven patients with the repetitive type. All patients were treated with between one and eight (median three) antiarrhythmic drugs. The most effective drug was amiodarone, followed by the class I C antiarrhythmic drugs, propafenone and flecainide. At present, all patients are alive 4 months to 21 years (median 2.5 years) after diagnosis of AAT. Twelve patients are in sinus rhythm, five of them without any medication. Nine patients still have AAT, which, however, is repetitive or intermittent in all but one. In conclusion, AAT is an unusual, and in its incessant form often severely symptomatic arrhythmia, which is resistant to conventional antiarrhythmic medication. However, amiodarone and class I C antiarrhythmic drugs are frequently effective. Since medical treatment with these drugs is often successful, and AAT may resolve completely, a conservative approach is indicated in many cases.

Adolescent↗
PubMed1992

Strong trans activation of the human cytomegalovirus major immediate-early enhancer by p40tax of human T-cell leukemia virus type I via two repetitive tax-responsive sequence elements.

The immediate-early 1 and 2 gene locus of human cytomegalovirus (HCMV) that encodes trans-activator proteins with effects on both homologous and heterologous promoters is expressed under control of a complex enhancer/promoter regulatory region. This enhancer contains four types of repetitive sequence elements with 17, 18, 19, and 21 bp that bind cellular transcription factors. Although the HCMV enhancer acts as a powerful stimulator of transcription in most cell types examined, human T cells do not support strong activity. The present study demonstrates that the tax gene product of human T-cell leukemia virus type I trans activates the major enhancer of HCMV more than 60-fold in the T-cell line Jurkat. When a series of chloramphenicol acetyltransferase expression plasmids containing synthetic oligonucleotides with the 17-, 18-, 19-, or 21-bp motif upstream of a minimal immediate-early 1 and 2 gene promoter was tested, two of the four repeat motifs could be identified as Tax-responsive elements. Both the 18- and the 19-bp motifs were able to act as strong Tax-responsive elements even when they were present as single copies. Thus, in addition to interacting with human immunodeficiency virus, HCMV is able to interact with a second retrovirus of clinical importance.

Avian Sarcoma Viruses↗
PubMed1992

Correlation between echocardiographic and morphological investigations of lesions of the tricuspid valve diagnosed during fetal life.

OBJECTIVE: To assess the degree of agreement between the fetal echocardiographic and postmortem examination of hearts from fetuses with severe malformations of the tricuspid valve. DESIGN: A retrospective study to analyse echocardiographic recordings and make comparisons with postmortem findings. SETTING: Tertiary referral centre for fetal echocardiography. Institute for cardiac morphology. PATIENTS: 19 cases shown to have severe malformation of the tricuspid valve by fetal echocardiography that died in the prenatal or neonatal period. MAIN OUTCOME MEASURES: Correlations between morphology and measurements made at echocardiography and necropsy. RESULTS: The echocardiographic diagnosis was Ebstein's malformation in seven and tricuspid valvar dysplasia in 12 fetuses. These findings were confirmed in six and eight cases at necropsy. In one false positive diagnosis of Ebstein's malformation, necropsy showed dysplasia of the leaflets of the tricuspid valve without displacement. In four cases with the echocardiographic diagnosis of valvar dysplasia, necropsy showed displacement, the hallmark of Ebstein's malformation. Associated malformations that are known to worsen prognosis were predicted correctly by echocardiography. Taking the mean duration of four weeks between echocardiographic and postmortem investigations, both methods showed cardiomegaly causing lung hypoplasia, right atrial dilatation, and relative hypoplasia of the pulmonary trunk, morphometric factors that may be responsible for the poor outcome. Mostly good agreement existed between the echocardiographic and postmortem measurements if cases with an interval of more than eight weeks between the measurements were excluded. CONCLUSION: Fetal echocardiography was proved to be a reliable technique in differentiating the variants of tricuspid valvar disease, in diagnosing associated cardiac lesions, and in predicting quantitative factors that can define the subsequent outcome.

Ebstein Anomaly↗
PubMed1992

Shunt implantation: reducing the incidence of shunt infection.

Shunt infection remains the foremost problem of shunt implantation after mechanical malfunctions. Diversionary cerebrospinal fluid shunt implantation has a high complication rate, with 5% to 15% of such shunts becoming infected. Of these infections, 70% are diagnosed within 1 month after surgery and more than 90% within 6 months. Shunt infection in the vast majority of cases is therefore a complication of shunt surgery. The authors review their experience with shunt implantation during two time periods. From January, 1978, to December, 1982, 302 children with hydrocephalus underwent 606 operations. Among these children, 47 (15.56%) developed a proven shunt infection, with an incidence of infection per procedure of 7.75%. As a result of this study, a new protocol for shunt procedures involving modifications in the immediate pre-, intra-, and postoperative management of children undergoing shunt implantation was initiated. With this new protocol, 600 children underwent a total of 1197 procedures between January, 1983, and December, 1990. The incidence of shunt infection decreased dramatically, with two infections (0.33%) in 600 patients and a per-procedure rate of 0.17%. The overall annual risk of a shunt infection in the pediatric neurosurgical unit is currently 1.04%.

Bacterial Infections↗
PubMed1991

Human lymphocyte reactivity after in vitro exposure to technical and analytical grade pentachlorophenol.

To investigate the potential effects of technical pentachlorophenol (PCP-T, contaminated with polychlorinated dioxins and furans) and of analytical grade pentachlorophenol (PCP-A) on the human immune system, in vitro assays with freshly prepared human peripheral blood lymphocytes were used as an alternative to experimental animals. Both cell-mediated and humoral immune functions were examined after direct lymphocyte exposure to PCP-T or PCP-A at concentrations ranging from 0-200 microM. In each case the viability of the treated cells remained within the control value range. T lymphocyte blastogenesis after 3 days incubation with PCP was measured using both optimal and suboptimal mitogen (PHA) concentration. Interleukin-2 activity of 24.5-h supernatants of lymphocytes in response to PHA, pretreated with PCP for 20-24 h, was examined in a bioassay using the mouse IL-2-dependent CTLL-6 cell line. The synthesis of immunoglobulins was determined after stimulation with T-dependent (PWM) and T-independent (KlebsM) polyclonal B cell activators. In the proliferation assay the effects of PCP-T became more evident after suboptimal mitogen stimulation. Whereas after optimal mitogen stimulation blastogenesis was affected only at the highest concentration of 200 microM PCP-T, cell reactivity after suboptimal PHA stimulation was altered by all PCP-T doses. In the lower concentration range PCP-T caused enhanced proliferative responses, but at the two highest PCP-T concentrations cell reactivity was significantly suppressed as compared to the medium controls. Significant differences between the effects of PCP-T and PCP-A could be demonstrated only after optimal mitogen stimulation at the highest PCP concentration (200 microM). In contrast, lymphokine production as well as Ig secretion showed severe dose-dependent suppression after exposure to both PCP-T and PCP-A. The humoral immune response appeared to be more suppressed when cultures were stimulated with T-dependent rather than T-independent mitogens. The two different PCP preparations caused immunosuppression of both lymphocyte functions to the same extent. To summarize, the results of our studies indicate that PCP itself is directly immunotoxic to human immunocompetent cells and the T helper cell subset appears to be especially sensitive to PCP exposure. Furthermore, the observation of a direct effect on humoral immunity is similar to previous results showing considerable alterations of antigen specific antibody production in experimental animals after in vivo exposure.

Cell Survival↗
PubMed1991

Pathologic spectrum of malformations of the tricuspid valve in prenatal and neonatal life.

The morphologic spectrum of malformations of the tricuspid valve in 14 fetal and 5 neonatal heart specimens is described. Echocardiography during fetal life had revealed the valvular malformations along with dilation of the right-sided chambers of the heart and atrioventricular (AV) valve incompetence. This functional impairment reflected either Ebstein's malformation (10 cases) or dysplasia of valve leaflets having a normal junctional attachment (9 cases). The right atrium and right ventricle were markedly enlarged, and heart weight was increased to 181% (median) and 179% (median) in the groups with Ebstein's malformation and valvular dysplasia, respectively. In contrast, lung weight was in the lower range of normal, showing a decrease of 67% (median) in patients with Ebstein's malformation and of 43% (median) in those with valvular dysplasia. One ventricular septal defect and six atrial septal defects were noted in each group. Severe obstruction at the level of the pulmonary valve was seen in 40% of the group with Ebstein's malformation and in 66% of those with valvular dysplasia. The most important factor in the particularly poor prognosis in these patients is the incompetence of the tricuspid valve, leading to right atrial enlargement and subsequent pulmonary hypoplasia. No significant difference was found between the pathologic features of fetal and neonatal hearts and no features that might have prompted the valve to become regurgitant during fetal life were identified.

Abnormalities, Multiple↗
PubMed1991

Inhibition of inositol 1,4,5-trisphosphate formation by cyclic GMP in cultured aortic endothelial cells of the pig.

1. In cultured endothelial cells of the pig the endothelium-derived relaxing factor (EDRF) releasing agent thrombin (2 u ml-1) caused a significant increase in basal levels of both guanosine 3':5'-cyclic monophosphate (cyclic GMP) and inositol 1,4,5-trisphosphate (IP3). This increase was time dependent, with peak levels occurring at 2 min and returning towards basal values after 5 min. 2. Pretreatment of the cells with the EDRF inhibitors haemoglobin (1 microM) or L-NG-nitro arginine (50 microM) significantly reduced the cyclic GMP response to thrombin. Both agents also resulted in significant elevations in basal levels of IP3. The IP3 response to thrombin was significantly enhanced at all time points by haemoglobin and at 5 min for L-NG-nitro arginine, when compared with the response to thrombin alone. 3. Pretreatment of the cells with either sodium nitroprusside (10 microM) or atrial natriuretic peptide (1 microM) caused a significant elevation of basal cyclic GMP levels. Although subsequent exposure to thrombin caused a further increase in cyclic GMP, which together with the rise induced by the previous two agents was significantly greater than the increase caused by thrombin alone, the incremental increase induced by thrombin was markedly less in the presence of nitroprusside or atrial natriuretic peptide. Both these agents, as well as 8-bromo cyclic GMP, resulted in a significant suppression of the IP3 response to thrombin. 4. These findings show that one mechanism for the inhibitory effect of cyclic GMP on EDRF release from endothelium may be through the inhibition of IP3 formation in response to EDRF releasing agents.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Endothelium-derived relaxing factor inhibits the endothelin-1-induced increase in protein kinase C activity in rat aorta.

1. Particulate and cytosolic protein kinase C (PKC) activity was measured in rat aortae with and without endothelium, following exposure to endothelin-1 (10(-8) M) for various time intervals. 2. Endothelin-1 induced two peaks of particulate PKC activity, occurring at 30 s and 10 min exposure times in both endothelium-intact and endothelium-denuded preparations. Cytosolic PKC activity fell below baseline at all incubation times studied. 3. In endothelium-denuded preparations, elevation of guanosine 3':5'-cyclic monophosphate (cyclic GMP) levels with sodium nitroprusside (10(-6) M) or atrial natriuretic peptide (10(-6) M) and, in endothelium-intact preparations with the calcium ionophore A23187 (10(-6) M), inhibited the activation of particulate PKC activity seen after incubation with endothelin-1 for 30 s. The inhibitory effect of A23187 was prevented by prior incubation of the endothelium-intact vessels with the nitric oxide synthetase inhibitor, L-NG-nitro arginine (5 x 10(-5) M). 4. These results indicate that EDRF acting via cyclic GMP can inhibit the activation of PKC induced by endothelin-1 in rat aorta.

Animals↗
PubMed1990

The Marfan syndrome--analysis of growth and cardiovascular manifestation.

Forty-eight children and adolescents (mean age 10.5 years, range 1.25-18 years) with clinical evidence of Marfan syndrome were studied. Height and weight percentiles were established. Cardiac dimensions and morphology were studied by M-mode and 2D-echocardiography. At diagnosis left atrial and left ventricular end-diastolic diameter and left ventricular posterior wall thickness were within normal limits except in a few adolescent patients. Interventricular septum was thickened in about 20% and aortic diameter increased in 56% of the patients. An additional 13% of patients developed aortic dilation during the study period. At diagnosis regression analysis revealed a significant (P less than 0.05) correlation of the aortic diameter, septal thickness and the posterior left ventricular wall thickness and body surface area. Follow up studies of 19 patients allowed documentation of the development of aortic root dilation.

Adolescent↗
PubMed1990

Release of endothelium-derived relaxing factor from pig cultured aortic endothelial cells, as assessed by changes in endothelial cell cyclic GMP content, is inhibited by a phorbol ester.

1. Cultured aortic endothelial cells of the pig respond to the endothelium-derived relaxing factor (EDRF) they release with an increase in cyclic GMP content. This response is inhibited by haemoglobin or by L-NG-monomethyl-arginine (L-NMMA), and has been used to investigate the effects of phorbol esters on EDRF release. 2. Pretreatment with phorbol-12,13-dibutyrate (PDB) but not the inactive 4 alpha-phorbol-12,13,-didecanoate (PDD), inhibited increases in cyclic GMP induced by substance P (10(-8) M) in a time and concentration-dependent manner. PDB did not affect basal cyclic GMP levels. 3. PDB (3 x 10(-7) M), but not PDD (3 x 10(-7) M), also inhibited ATP (10(-5) M)-induced increases in cyclic GMP, but did not affect those induced by bradykinin (10(-7) M). 4. Increases in cyclic GMP induced by low (10(-7) M) but not high (10(-6) M) concentrations of the calcium ionophore A23187 were inhibited by PDB (3 x 10(-7) M). This inhibitory effect was due to enhanced destruction of EDRF by superoxide anions rather than inhibition of EDRF release, as the inhibition was abolished in the presence of superoxide dismutase (SOD, 30 mu ml-1) and catalase (CAT, 100 mu ml-1). 5. SOD and CAT did not affect the inhibitory action of PDB on substance P or ATP-induced increases in cyclic GMP. 6. Increases in endothelial cell cyclic GMP content induced by sodium nitroprusside (10(-5) M) were unaffected by PDB pretreatment. 7. The inhibitory effects of PDB are probably a result of an action of protein kinase C on the steps between receptor occupation and phospholipase C activation.

Adenosine Triphosphate↗
PubMed1989

The diameter of coronary arteries in infants and children without heart disease.

Two-dimensional echocardiographic examinations of the proximal left and right coronary artery were performed in 100 children without heart disease. Fifty-nine boys and 41 girls were studied whose ages ranged from 1 day to 17 years old. The diameter of the proximal right and left coronary artery was 1 mm in newborns and 4.5 mm in teenagers. No significant difference was observed between male and female subjects. A linear correlation between the coronary artery dimensions and the patient's age, weight, length, and body surface area could be demonstrated. The closest linear correlation corresponded to the patient's length with a correlation coefficient of r = 0.91 and r = 0.89 for the right and the left proximal coronary artery respectively. A quick orientation concerning normality of coronary artery diameters is possible with our graph of body length and corresponding coronary artery size. Knowing normal echocardiographic values for proximal coronary artery diameters, even subtle changes of these vessels can be diagnosed and the number of invasive diagnostic procedures, e.g. in Kawasaki disease, can be reduced.

Adolescent↗
PubMed1989

Osteogenesis imperfecta in childhood: cardiac and renal manifestations.

We examined 58 children aged 1-16 years with various forms of osteogenesis imperfecta (OI). Congenital cardiac malformations were diagnosed in 4 children (valvular aortic stenosis, 2 with atrial septal defect II, Fallot Tetralogy). Two additional children developed holosystolic mitral valve prolapse and regurgitation. Children suffering from a severe clinical course (type III according to the Sillence classification) showed aortic root dilatation (28%) and increased septal (40%) and posterior left ventricular wall thickening (68%) on initial evaluation. All three parameters were significantly correlated to body surface area. Kidney stones and renal papillary calcifications were detected in 4 children. Cardiovascular abnormalities and nephrolithiasis may be important extraskeletal manifestations of childhood OI.

Adolescent↗
PubMed1989

Diagnostic criteria of interatrial defects: a single gate pulsed Doppler echocardiographic study.

Functional closure of the oval foramen occurs during the first days of life. Nevertheless, range-gated pulsed Doppler echocardiography shows a transatrial flow pattern in many newborns. In this situation, cross-sectional echocardiography often fails in differentiating the valve-incompetent oval foramen from an atrial septal defect. In order to establish Dopplersonographic criteria for these diagnoses, we performed a prospective echocardiographic and pulsed Doppler study in 34 newborns with valve-incompetent oval foramen and in 30 children with atrial septal defect. We could not find any significant difference of flow pattern in either group, although a so-called "flap" signal could be demonstrated in 73.5% of the patients with an oval foramen, but in only 23% of the children with atrial septal defect. We suggest this feature reflects a distinct movement of the flap of oval foramen which passively follows the different interatrial pressure-flow dynamics. Nevertheless, this sign was insufficiently constant to prove presence of an oval foramen and not that specific to exclude an atrial septal defect. We conclude, therefore, that the precise nature of interatrial defects cannot be differentiated by single gate pulsed Doppler echocardiography.

Echocardiography↗
PubMed1989

Flexor tendon repair in zone 2 followed by controlled active mobilisation.

Over a two-year-period, 34 adult patients who had suffered zone two flexor tendon injuries to 38 fingers (70 tendons) were managed post-operatively by a regime of early active mobilisation. The results of this technique, assessed by the Strickland criteria after a mean follow-up period of 10.2 months, compared favourably with other more cumbersome methods.

Adolescent↗