The enamel knot as a signaling center in the developing mouse tooth.

Mammalian tooth forms are produced during development by folding of the enamel epithelium but the molecular mechanisms involved in the formation and patterning of tooth cusps are not understood. We now report that several key signaling molecules found in well-known vertebrate signaling tissues such as the node, the notochord, the apical ectodermal ridge, and the zone of polarizing activity in the limb bud are specifically expressed in cells of the enamel knot, which is a transient cluster of dental epithelial cells. By comparing three-dimensional reconstructions of serial sections following in situ hybridization we localized Sonic hedgehog, Bone morphogenetic proteins-2, -4 and -7, as well as Fibroblast growth factor-4 in nested domains within the enamel knot. We suggest that the enamel knot acts as a signaling or organizing center, which provides positional information for tooth morphogenesis and regulates the growth of tooth cusps.

Runx2 (Cbfa1) inhibits Shh signaling in the lower but not upper molars of mouse embryos and prevents the budding of putative successional teeth.

Heterozygous mutations in the RUNX2 (CBFA1) gene cause cleidocranial dysplasia, characterized by multiple supernumerary teeth. This suggests that Runx2 inhibits successional tooth formation. However, in Runx2 knockout mice, molar development arrests at the late bud stage, and lower molars are more severely affected than upper ones. We have proposed that compensation by Runx3 may be involved. We compared the molar phenotypes of Runx2/Runx3 double-knockouts with those of Runx2 knockouts, but found no indication of such compensation. Shh and its mediators Ptc1, Ptc2, and Gli1 were down-regulated only in the lower but not the upper molars of Runx2 and Runx2/Runx3 knockouts. Interestingly, in front of the mutant upper molar, a prominent epithelial bud protruded lingually with active Shh signaling. Similar buds were also present in Runx2 heterozygotes, and they may represent the extension of dental lamina for successional teeth. The results suggest that Runx2 prevents the formation of Shh-expressing buds for successional teeth.

Comparison of expression of the msx-1, msx-2, BMP-2 and BMP-4 genes in the mouse upper diastemal and molar tooth primordia.

The existence of transient putative tooth anlagen in the prospective mouse upper diastema region has been documented previously in morphological studies. By in situ hybridization we investigated the expression patterns of the msx-1, msx-2, BMP-2 and BMP-4 genes, supposed to regulate early tooth development, in day 10-14 mouse embryonic upper diastema and molar regions, using 49 series of frontal sections. On the basis of comparison of the temporo-spatial expression patterns in both diastemal and molar tooth primordia we conclude that each of the four genes was expressed at least for some period simultaneously and at a comparable developmental stage in the transient and persisting dental primordia. BMP-2 and BMP-4 expression was downregulated in the diastemal dental primordia during their regression starting at day 13. The temporo-spatial pattern of BMPs expression may be associated with the disappearance of diastemal rudiments. Contrary to the molar anlage, we did not detect msx-2 gene expression in the diastemal dental rudiments after the stage of epithelial thickening. The deficiency of the msx-2 gene products may play a role in the growth retardation of diastemal dental primordia resulting in their subsequent involution.

Argyrophil carcinoid tumors of the lung. Incidence, clinical study, and follow-up of 46 patients.

Forty-nine patients with lung tumors initially diagnosed as carcinoids from their cellular appearance and arrangement were originally included in the study. The tumors of 46 of these patients showed an argyrophil reaction with the Grimelius silver stain. The three nonargyrophil tumors were reclassified as noncarcinoid tumors at further examination. The use of the argyrophil technique in characterization of the lung carcinoid tumors is discussed. The incidence of lung carcinoid tumors in the County of Uppsala was 0.7 patients per 100,000 inhabitants per year. Eleven patients with detected disease were symptom-free. The doctor's delay in 9 patients was 3 to 13.8 years. Yet, the prognosis was good, with 5-year survival in 91 percent, 10-year survival in 91 percent, and 15-year survival in 86 percent of the 46 surgically-treated patients. It is concluded that the surgical treatment should at least comprise a lobectomy.

Adverse effects on the brain in cardiac operations as assessed by biochemical, psychometric, and radiologic methods.

In order to describe subclinical brain injury in conjunction with cardiac operations 94 patients were prospectively studied with three brain injury assessment methods: CSF analyses 24 hours after bypass, psychometry, and computed tomography of the brain. Adenylate kinase (AK), a marker of ischemic brain cell injury, was measured in cerebrospinal fluid (CSF) and in serum. In 13% of the patients, a considerable increase in CSF-AK was seen, in 46% there was a moderate increase, and in 41% no or trivial increase. Psychometry measured as change between preoperative scores in a test battery (SS3) revealed a moderate decrease in intellectual function after operation. There was a significant inverse correlation between CSF-AK and SS3 (r = -0.46, p less than 0.001, r2 = 0.21, n = 71). Computed tomography (CT) of the brain was performed preoperatively and postoperatively in 54 patients. Two of these had cerebral infarctions visible on the CT, despite an essentially normal postoperative state. There was no correlation between indices of brain injury and patient diagnosis and length of perfusion. It is concluded that subclinical brain injury is often seen after cardiac operations. Most often the injury appears trivial and/or reversible, but in a minority of cases there is evidence that the brain injury is irreversible. Factor analysis favors the view that the microembolism theory might no longer be a valid concept in modern cardiopulmonary bypass (CPB). Instead, circumstances in the operative field seem more likely to be important causative factors. This interpretation calls for new principles in the search for an improved cerebral protection during cardiac operations.

Development of granulomas and vascular fibrocellular proliferation in the lungs of pigs receiving long-term lipid-based parenteral nutrition.

The lungs of pigs receiving long-term total parenteral nutrition (TPN) have been studied. A total of 20 pigs were tentatively infused with TPN through central venous catheters for 7 weeks. To secure adequate nutrition and gastrointestinal absorbance of nutrients, an additional full oral diet was given to eight of these animals. Fifteen control animals received Ringer solution through central venous catheters in addition to the oral diet. All animals infused with TPN for 7 weeks developed lung granulomas, a finding not observed in control animals. No lung granulomas were seen in three TPN animals sacrificed after 3 to 5 weeks owing to illness. All TPN animals also developed tissue reactions suggesting long-standing lung vascular inflammation. Similar vascular changes were seen in seven control animals that had bacterial infection or endotoxemia. The total amount of neutral fat in lung homogenate tended to increase in animals given TPN, and the linoleic acid content was significantly increased. In conclusion, long-term TPN caused lung granulomas in pigs. Vascular damage seemed to be accelerated by bacterial infection as well as by the TPN. The tissue reactions presumably involved long-term activation of monocytes/macrophages.

Influence of a diet regimen on glucose homeostasis and serum lipid levels of male elite athletes.

Physical training affects carbohydrate metabolism and results in an increased insulin-stimulated glucose disposal. To investigate if carbohydrate and lipid metabolism would be affected by nutritional factors in optimally trained elite athletes, during a 1-year period we studies elite ice-hockey players on two Swedish top-performance teams. Players on one team were subjected to extensive dietary monitoring and intervention, whereas players on the second team continued their ordinary diet. Blood levels of insulin, C-peptide, glucose, hemoglobin A1C (HbA1c), lipids, and lipoproteins were measured repeatedly. Basal insulin levels and insulin resistance (IR) were significantly lower among athletes on both teams compared with a sedentary group, and muscle weight and body mass index were significantly higher. During the course of the study in the intervention group, insulin levels decreased (3.6 +/- 0.3 v 6.2 +/- 0.6 [mean +/- SEM], P <.05) in conjunction with a decreased relative fat energy content, but returned toward baseline levels when relative fat energy content increased. IR decreased in parallel (0.59 +/- 0.05 v l.12 +/- 0.12, P <.05) and followed a similar pattern, reverting toward baseline levels. Also, levels of HbA1c changed during dietary manipulation. No changes in these parameters were observed among the elite players from the team not participating in the diet regimen. In contrast to the parameters for glucose homeostasis, no significant changes were found in serum lipid or lipoprotein levels in either team during the course of the study. The results verify the presence of an improved carbohydrate metabolism in elite athletes. The observed changes in glycemic control and glucose homeostasis as a consequence of dietary modification demonstrate further that nutritional factors may affect carbohydrate metabolism also in well-trained athletes.

Signs of brain cell injury during open heart operations: past and present.

Signs of brain cell injury have been studied during the evolution of open heart surgery in the last quarter century. At the beginning of the period, it was possible to elucidate signs of brain injury with rather crude psychometric tests and clinical observations in seemingly normal patients having routine operations. Over the next 5 years, a marked improvement in psychometric scores was observed. However, a biochemical cerebral cell injury marker (adenylate kinase) showed increased levels in the cerebrospinal fluid, a finding indicative of brain cell injury. There was a correlation between cerebrospinal fluid levels of adenylate kinase and psychometric test results as well as between the marker levels and clinical signs. Because of the relative insensitivity of the psychometric tests used and the increasing difficulty in receiving permission for spinal fluid taps, other methods were sought. Refined psychometric memory tests were used and showed that even in the 1990s, there are subtle signs of brain cell injury during open heart operations. This finding was corroborated by using a highly brain-specific and brain-sensitive biochemical cell injury marker (S-100 beta) that increased during extracorporeal circulation and showed a correlation with clinical cerebral complications.

Transventricular aortic cannulation for repair of aortic dissection.

We have used transventricular aortic cannulation as arterial inflow from the heart-lung machine in seven consecutive operations done in 1 year for acute aortic dissection. Satisfactory cardiopulmonary bypass was achieved in all patients.

Intellectual function late after open-heart operation.

Cerebral emboli are not uncommon complications after valve replacements. We investigated the hypothesis that there are emboli that are clinically unnoticeable but that may affect the intellectual function of the brain. One hundred sixty-five patients were studied with a battery of psychometric tests before and after operation, two months postoperatively, and 2 to 8 years after operation. Ten patients sustained late cerebral infarction or hemorrhage. Their late intellectual function was low, indicating an impairment in brain performance. The remaining 155 patients had had no cerebral complications postoperatively. Eighty-three had had valve replacement (Björk-Shiley valves); 51, aortocoronary bypass operations; and 21, closure of an atrial septal defect (all adult patients). Late intellectual function was significantly lower in the patients with a valve prosthesis than in the other two groups. However, this difference could be traced back to the operation. Thus, we have not been able to confirm our hypothesis that late intellectual function in patients with a heart valve prosthesis deteriorates as a result of clinically silent emboli. On the contrary, patients who have undergone aortocoronary bypass operation sustain more deterioration in late intellectual function than the other groups. Late intellectual function in this study population clearly was influenced by events during the operation. Because cerebral injury can be shown almost regularly after open-heart operation, this investigation provides an incentive for further efforts to improve the quality of open-heart surgery with the aim of keeping brain function as intact as possible.

The choice of operation for bronchial carcinoids.

In a review of the literature, 1,392 patients with bronchial carcinoids were found. Of these, there were 313 patients for whom individual data with regard to type of operation, follow-up period, and outcome were given. Actuarial curves for proportions of patients who had not died of the disease or who had not undergone reoperation for residual disease were constructed for each type of operation. The prognosis up to 20 years after surgical treatment for bronchial carcinoids is excellent. For 15 to 20 years postoperatively, the prognosis after a lobectomy is excellent and after a pneumonectomy, slightly worse. The prognosis after a lung parenchyma-saving operation (wedge or segmental resection and bronchoplastic procedures) is similar to that after a lobectomy up to 7 years postoperatively. After that, the proportion of disease-free patients declines precipitously. At 20 years the difference in comparison with a lobectomy is statistically significant for both wedge or segmental resections and bronchoplastic procedures. Parenchyma-saving operations cannot therefore be said to be radical. A policy for decision-making at the operating table is formulated.

The effect of metastasectomy: fact or fiction?

Metastasectomy in the treatment of solitary metastases has been recommended almost unanimously. The basis for this recommendation has been that 5-year survival after metastasectomy is around 30%, which is just as good as after operation for bronchial carcinoma. It has been assumed, implied, or claimed that the 5-year survival without operation is nil. Control material is, however, lacking. Seventy surgically treated patients were compared with a small, historical control group of 12 patients. There was no difference in 5-year survival. Because of these findings and after a study of the literature, we postulate that patients with lung metastases fulfilling the criteria for operation constitute a selected group with a favorable natural history. Five-year survival, therefore, is an insufficient way of describing the effect of metastasectomy. However, patients with 10-year survival are rare in the literature. In some patients with a favorable tumor-host relationship or with possibilities for effective chemotherapy, cure or prolongation of life has been achieved. Such patients should undergo operation. Randomized studies are needed in all groups for which we do not have sufficiently strong evidence that metastasectomy contributes to the longevity of the patient.

Appropriateness of referral of coronary angiography patients in Sweden. SECOR/SBU Project Group.

OBJECTIVE: To evaluate the appropriateness of referral following coronary angiography in Sweden. DESIGN: Prospective survey and review of medical records. PATIENTS: Consecutive series of 2767 patients who underwent coronary angiography in Sweden between May 1994 and January 1995 and were considered for coronary revascularisation. MAIN OUTCOME MEASURES: Percentage of patients referred for coronary artery bypass graft surgery (CABG) and percutaneous transluminal coronary angioplasty (PTCA) for indications that were judged necessary, appropriate, uncertain, and inappropriate by a multispecialty Swedish national expert panel using the RAND/University of California Los Angeles (UCLA) appropriateness method, and the percentage of patients referred for continued medical management who met necessity criteria for revascularisation. RESULTS: Half the patients were referred for CABG, 25% for PTCA, and 25% for continued medical therapy. CABG was judged appropriate or necessary for 78% of patients, uncertain for 12% and inappropriate for 10%. For PTCA the figures were 32%, 30% and 38%, respectively. Two factors contributed to the high inappropriate rate. Many of these patients did not have "significant" coronary artery disease (although all had at least one stenosis > 50%) or they were treated with less than "optimal" medical therapy. While 96% of patients who met necessity criteria for revascularisation were appropriately referred for revascularisation, 4% were referred for continued medical therapy. CONCLUSIONS: Using the RAND/UCLA appropriateness method and the definitions agreed to by the expert panel, which may be considered conservative today, it was found that 19% of Swedish patients were referred for coronary revascularisation judged inappropriate. Since some cardiovascular procedures evolve rapidly, the proportion of patients referred for inappropriate indications today remains unknown. Nevertheless, physicians should actively identify those patients who will and will not benefit from coronary revascularisation and ensure that they are appropriately treated.

Intracaval paraganglioma causing superior vena cava syndrome.

We report a 46-year old female patient with progressive symptoms and signs of superior caval syndrome. At surgery, the caval vein with a benign intravascular paraganglioma was removed, and a venous interposition using a spiral vein graft was performed.

Routine registration of deviations from the norm in cardiac surgery: a potent clinical research tool and quality assurance measure.

UNLABELLED: The surveillance and monitoring of deviations from normality is an often used quality assurance weapon in private industry. In cardiac surgery, complications have often been monitored and reported, but mostly one at a time and in conjunction with a scientific study. METHODS: Using the clinic's data network including operating theatre, intensive care unit and ward, deviations from a normal postoperative course are registered by the patient's nurses. The deviations are registered by answering questions on all organ systems in front of a PC. Suitable definitions are available to the nurse. When the patient is discharged, the surgeon in charge will review the deviations noted and make a formal diagnosis on the patient's chart if appropriate. RESULTS: The data system has now been in use for 6 months. It was easily adopted by the nurses. The doctor's work is facilitated as relevant data are available to him when discharging the patient and making the discharge note. 58% of the patients have some kind of deviation from the norm, most commonly in the cardiovascular system (30% of the patients), respiratory system (22%), and surgically complicated postoperative course (17%). During the first months of registration it became apparent that too many patients had postoperative thrombophlebitis. By changing routines, the incidence of thrombophlebitis decreased from 5 to < 1%. CONCLUSION: Only about 40% of our patients go through a cardiac operation with a totally normal postoperative course. The registration system has turned out to be easily handled by our nurses and able to detect complications not immediately noticed in everyday clinical practice. A registry of this kind is highly dependent on its definitions and on the general 'norm' prevailing. Findings from such registries cannot therefore be immediately compared with those of other institutions. The research potentials of the registry as well as its role in quality assurance seem large.

CABG in chronic stable angina pectoris patients: indications and outcomes (SECOR/SBU). Swedish Societies for Cardiology, Thoracic Radiology and Thoracic surgery/Swedish Council for Technology Assessment in Health Care.

OBJECTIVE: In order to ascertain the reasons why coronary revascularisation is performed, the appropriateness of these procedures and their outcomes, a national collaborative study encompassing 7 of 8 hospitals performing CABG in Sweden was undertaken. This article presents the indications and outcomes in the largest intervention group, chronic stable angina pectoris treated by first time CABG. METHODS: A prospective multi-centre study was carried out during a 3.5 month period in each centre. Patients (1039) with chronic stable angina pectoris undergoing first time CABG were enrolled. Patients' quality of life was recorded at the time they underwent angiography and again 6 months post-operatively. Mortality and serious peri-and post-operative complications were recorded. The study was designed and carried out by an independent government agency, the Swedish Council for Technology Assessment in Health Care (SBU) with a project group of representatives for the Swedish Societies for Cardiology, Thoracic Radiology and Thoracic Surgery. RESULTS: Median age was 66 years. A total of 80% were males. The mortality rates at 30 days and 6 months were 1.0 and 1.9%, respectively. A balloon pump was used for 0.9% of patients and 1.4% of them were on a respirator for more than 24 h. At recruitment, 43.9% of the patients reported having severe angina (CCS II/IV), 70.1% had angina > or = 3 times per week, and 53.1% used sublingual nitrates > or = 3 times per week. The corresponding results at 6 months were 6.7, 10.5 and 3.3%, respectively. Patient satisfaction with operative treatment was high. In comparison with the pre-operative status, quality of life was markedly improved after surgery. CONCLUSION: This study shows that CABG in chronic stable angina pectoris yields good outcomes with a low mortality and morbidity and a high degree of patient satisfaction and quality of life.

Neurological and general outcome in low-risk coronary artery bypass patients using heparin coated circuits.

OBJECTIVE: The clinical significance of heparin coating in cardiopulmonary bypass has previously been investigated. However, few studies have addressed the possible influence on brain function and memory disturbances. METHODS: Three hundred low-risk patients exposed to coronary bypass surgery were randomised into three groups according to type of heparin coating: Carmeda Bioactive Surface, Baxter Duraflo II and a control group. Outcome was determined from a number of clinically oriented parameters, including a detailed registry of postoperative deviations from the normal postoperative course. Brain damage was assessed through S100 release and memory tests, including a questionnaire follow-up. RESULTS: Clinical outcome was similar for all groups. Blood loss (Duraflo only), transfusion requirements and postoperative creatinine elevation were reduced in the heparin-coated groups. A lower incidence of atrial fibrillation was noted in the Duraflo group. Heparin coating did not uniformly attenuate the release of S100 or the degree of memory impairment. CONCLUSIONS: Cardiopulmonary bypass (CPB) with heparin coating and a reduced dose of heparin seems to be safe. Clinical outcome and neurological injury seem not to be associated with type of heparin coating used for CPB. However, blood loss and transfusion requirements may be reduced.

Clinical effects of the heparin coated surface in cardiopulmonary bypass.

OBJECTIVE: In a randomised study of 120 patients, undergoing primary operation for coronary heart decease, two groups were investigated as regards to the effects of heparin coated cardiopulmonary bypass on brain function parameters and general clinical outcome. The study group (n = 56) was perfused using an extra-corporeal circuit treated with covalent bonded heparin; the control group (n = 59) used an identical set-up without heparin treatment. Systemic heparin doses were calculated to achieve ACT levels of 250 and 500 s, respectively. Postoperative course was evaluated by examining a set of clinically relevant parameters including a detailed registry of postoperative deviations. Brain function was assessed by the biochemical marker S-100 and tests of memory performance. RESULTS: There were several signs of reduced operative trauma in the study group. Hospital stay was reduced by nearly 1 day (P < 0.05). Time on postoperative ventilatory support was approximately 4 h shorter (P = 0.009). Chest drain blood loss was decreased both at 8 (P = 0.01) and 24 h (P = 0.007) postoperatively. Body temperature was lower after surgery and especially on days 2 (P = 0.03) and 3 (P = 0.01). Perioperative creatinine elevation was significantly reduced (P = 0.03). Neurological deviations were fewer (P = 0.01). Brain function assessment revealed reduced plasma levels of S-100 both at termination of cardiopulmonary bypass (P = 0.008) and 7 h later (P = 0.04). However, no remediation of memory impairment could be demonstrated. CONCLUSIONS: Cardiopulmonary bypass with covalent bonded heparin attached to the extra-corporeal circuit in combination with a reduced systemic heparin dose seems to reduce safely and effectively the operative stress to the patient. There were also signs of improved cerebral protection.

Quality assurance in clinical perfusion.

OBJECTIVE: To investigate the properties and usefulness of prospective routine registration of incidents related to cardiopulmonary bypass and its clinical significance as a quality assurance instrument. METHODS: Incidents or deviations from the normal course observed during cardiopulmonary bypass procedures were registered in a computer database. Each incident was classified according to 14 pre-defined categories. The cause of each incident was evaluated, as well as patient outcome. Incidents leading to permanent or temporary injury were denoted accidents. The general- and category-related incidence rate was calculated for the observation period 1989-1997 encompassing 6918 cardiopulmonary bypass procedures. RESULTS: The general incidence rate varied between 4.5-7.6% per year during the registration period. Most incidents (57%) occurred during established, or start of, cardiopulmonary bypass, whereas the remaining proportion of incidents were detected either before (27%) or when terminating (16%). The most common category of incidents was oxygenator failure (1.6%), followed by mechanical (1.4%) and surgical (1.2%) incidents. Accidents and fatal outcomes occurred in 0.03% of the cases. CONCLUSIONS: Routine registration of incidents yields a clinically attractive instrument of controlling safety aspects and quality measures in cardiopulmonary bypass. The observed incidence rates are somewhat higher than previously reported, probably primarily related to the methodology implemented in this study.

A relative contra-indication to mediastinoscopy.

In a patient in whom a coarctation of the aorta had been successfully operated on 17 years earlier, a life-threatening haemorrhage from a thin-walled, dilated collateral artery occurred in conjunction with a mediastinoscopy. It is argued that diseases with increased mediastinal collateral vessels (coarctation of the aorta, cyanotic heart disease, severe suppurative lung disease) are relative contraindications to mediastinoscopy, even after a corrective procedure has been carried out.