Compositional and surface changes of retrieved stainless-steel hardware and its effects on surrounding soft tissues: A prospective study.

Purpose: To evaluate the surface, compositional, and histological changes in the overlying soft tissues of retrieved stainless-steel mini-plates and screws used for rigid internal fixation in the maxillofacial skeleton. Materials and Method: A prospective study was conducted comprising 60 patients who sustained maxillofacial trauma and underwent ORIF in our unit previously and who required hardware retrieval in the post-operative phase. The retrieved hardware was evaluated for surface and compositional changes with the help of a scanning electron microscope for surface roughness and corrosion changes. Energy-dispersive X-ray study was done to know the composition and metal release from the hardware. The data obtained from these results were compared with a control unused and a sterile stainless-steel mini-plate and screw. The effects of the corrosion changes of this hardware on the adjacent soft tissues were evaluated histologically to assess the cellular changes of the soft tissue cover overlying the stainless-steel mini-plates and screws. Results: A total of 96 stainless-steel mini-plates and 380 stainless-steel screws were retrieved from 60 patients. The control plate was smooth without any surface and corrosion defects, while the retrieved mini-plates irrespective of the reason for removal have shown surface roughness. Fe and Ni ions were found to be significantly reduced in the retrieved mini-plates. The presence of CrC in the retrieved plates indicates corrosion, which was seen only in hardware retrieved from symptomatic patients. The histological study revealed chronic inflammatory cell infiltrate with hyalinized connective tissue in all the samples irrespective of the reason for the removal of the plate. Conclusion: Stainless-steel mini-plates and screws act as a potent foreign body material and initiate a localized inflammatory reaction due to its corrosive products with longer duration of stay. Hence, the authors advocate the overall shift in the use of stainless-steel hardware to titanium hardware for ORIF.

Evolution of TNM Classification for Clinical Staging of Oral Cancer: The Past, Present and the Future.

Purpose: The AJCC (American Joint Committee on Cancer) Cancer Staging Manual, 1st Edition, was published in 1977 which focused on the TNM classification and staging of cancer to allow easy communication, formulation of a treatment plan and predict the prognosis, among the medical fraternity. Methods: Ever since the beginning, various modifications of the classification were introduced and released by the joint collaboration of AJCC and UICC (International Union Against Cancer) in various editions of cancer staging manuals. Results: The present review article was kept focused onto the changes introduced in the clinical staging of cancers of oral cavity. These changes came a long way since 1st edition 1944, to the eighth edition which was published in 2017. Conclusions: This article is a critical review on the past and present perspectives of the TNM classification of the oral cavity that were addressed and changed, adding a light on the future trends or necessary inclusions that would formulate a much easily acceptable and useful classification system.

Making consistent contacts to graphene: effect of architecture and growth induced defects.

The effects of contact architecture, graphene defect density and metal-semiconductor work function difference on the resistivity of metal-graphene contacts have been investigated. An architecture with metal on the bottom of graphene is found to yield resistivities that are lower, by a factor of four, and most consistent as compared to metal on top of graphene. Growth defects in graphene film were found to further reduce resistivity by a factor of two. Using a combination of method and metal used, the contact resistivity of graphene has been decreased by a factor of 10 to 1200 ± 250 [Formula: see text] using palladium as the contact metal. While the improved consistency is due to the metal being able to contact uncontaminated graphene in the metal on the bottom architecture, lower contact resistivities observed on defective graphene with the same metal are attributed to the increased number of modes of quantum transport in the channel.

Spotting 2D atomic layers on aluminum nitride thin films.

Substrates for 2D materials are important for tailoring their fundamental properties and realizing device applications. Aluminum nitride (AIN) films on silicon are promising large-area substrates for such devices in view of their high surface phonon energies and reasonably large dielectric constants. In this paper epitaxial layers of AlN on 2″ Si wafers have been investigated as a necessary first step to realize devices from exfoliated or transferred atomic layers. Significant thickness dependent contrast enhancements are both predicted and observed for monolayers of graphene and MoS2 on AlN films as compared to the conventional SiO2 films on silicon, with calculated contrast values approaching 100% for graphene on AlN as compared to 8% for SiO2 at normal incidences. Quantitative estimates of experimentally measured contrast using reflectance spectroscopy show very good agreement with calculated values. Transistors of monolayer graphene on AlN films are demonstrated, indicating the feasibility of complete device fabrication on the identified layers.

Pulmonary vagal innervation is required to establish adequate alveolar ventilation in the newborn lamb.

To investigate the effects of bilateral intrathoracic vagotomy on the establishment of continuous breathing and effective gas exchange at birth, we studied 8 chronically instrumented, unanesthetized, sham-operated and 14 vagotomized newborn lambs after a spontaneous, unassisted vaginal delivery. Fetal lambs were instrumented in utero to record sleep states, diaphragmatic electromyogram, blood pressure, arterial pH, and blood-gas tensions. Six of eight sham-operated lambs established effective gas exchange within 10 min of birth, whereas 12 of 14 vagotomized animals developed respiratory acidosis and hypoxemia (P = 0.008). Breathing frequency in vagotomized newborns was significantly lower during the entire postnatal period compared with sham-operated newborns. Vagotomized subjects also remained hypothermic during the entire postnatal period (P < 0.05). Bronchoalveolar lavage indicated an increased minimum surface tension, whereas lung histology showed perivascular edema and partial atelectasis in the vagotomized group. We conclude that stimulation of breathing and effective gas exchange are critically dependent on intact vagal nerves during the transition from fetal to neonatal life.

Somatosensory evoked potential monitoring during cardiac surgery: an examination of brachial plexus dysfunction.

OBJECTIVE: To observe the effects of the Favoloro and sternal retractors on the ulnar and median nerve somatosensory evoked potentials (SSEPs) and to identify any relationship with postoperative brachial plexus injury. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Twenty cardiac patients. INTERVENTIONS: SSEPs were studied in patients undergoing cardiac surgery using normothermic cardiopulmonary bypass. Evoked potentials were obtained from bilateral median and ulnar nerves. MEASUREMENTS: The incidence of nerve-specific SSEP changes and their temporal relationship to retractor usage were determined. The overall incidence of SSEP changes was 75%. There were no differences (p > 0.05) between the group showing changes (n = 15) and the group with no changes (n = 5) with respect to age, body surface area, weight, cross-clamp or cardiopulmonary bypass times. There also were no differences (p > 0.05) between the frequencies of left- and right-sided changes, or in nerve-specific SSEP changes. Seventy-four percent of SSEP changes correlated with retractor usage. No SSEP changes were associated with the Favoloro retractor. Significant SSEP depression, assessed by either percentage reduction in amplitude or persistent amplitude reduction, occurred in the absence of postoperative neurological deficits. There were no detected postoperative brachial plexus injuries. CONCLUSIONS: SSEP changes correlate with the use of the sternal retractor but not the Favoloro retractor. It was not possible to replicate the results of previous investigators in predicting postoperative neurological deficits based on the SSEP changes, and therefore the routine application of SSEP as a monitor cannot be recommended on the basis on these data.

Superoxide dismutase and catalase in protection of cardiopulmonary bypass-induced cardiac dysfunction and cellular injury.

BACKGROUND: Cardiac dysfunction following cardiopulmonary bypass (CPB) is well known. Various possible sources for increased levels of oxygen free radicals (OFRs) exist during CPB and OFRs depress cardiac function. Postpump (following CPB) cardiac dysfunction may be due to increased levels of OFRs. METHODS: This study investigated the effects of cold crystalloid cardioplegia with and without superoxide dismutase (SOD) and catalase (CAT) on cardiac function (cardiac index [CI], left ventricular work index [LVWI]), cardiac contractility (+dp/dt, +dp/dt/PAW [pulmonary arterial wedge pressure], +dp/dt/LVEDP [left ventricular end-diastolic pressure]), diastolic compliance (-dp/dt), OFR-producing activity of polymorphonuclear leukocytes (PMNL-CL); creatine kinase (CK) and MB isoenzyme of CK (MBCK), malondialdehyde (MDA), and white blood cells (WBC) and PMNLs from coronary sinus blood; and lactate levels in arterial blood in anesthetized dogs at various times (up to 90 mins) of reperfusion following 90 mins of hypothermic ischemic cardiac arrest. The dogs were divided into three groups: group I, sham bypass; group II, cold crystalloid cardioplegic cardiac arrest; group III, similar to group II but received SOD and catalase treatment. RESULTS: Postpump decreases in cardiac function, contractility and diastolic compliance were associated with increases in PMNL-CL activity, blood MDA, plasma CK and MBCK, and plasma lactate, and decreases in WBC and PMNLs. Prevention of postpump cardiac dysfunction (function and contractility) by SOD and CAT was associated with restoration in PMNL-CL activity, plasma CK and MBCK activity, and blood MDA towards control values although not complete. The levels of plasma lactate, total WBC and PMNLs were similar in group II and group III. CONCLUSIONS: These results suggest that postpump depression of cardiac function and contractility could be due to increased levels of OFRs and that SOD and CAT scavengers of superoxide anion and hydrogen peroxide respectively may be effective in preventing postpump cardiac dysfunction.

The effect of a synthetic analogue of prostaglandin E2 on wound healing in rats.

This was a prospective, randomized, double-blind experimental study to assess the effect of a long-acting prostaglandin (PG) analogue on wound healing in rats. Eight-cm long, dorsal midline skin incisions were made on rats (n = 44) and immediately resutured. The treatment group (n = 22) received daily intraperitoneal injections of 16,16-dimethyl prostaglandin E2-methyl ester (di-MPGE2) for 7 days, whereas the controls (n = 22) received normal saline. The rats were sacrificed in groups of 11 at 7 and 14 days, respectively. The wounds were excised and analyzed. Histology showed that there was increased fibrosis (p < 0.03) and a decreased number of macrophages (p < 0.02) in the PG group at 7 days. Tensile strength and hydroxyproline content also increased but did not attain significant levels. The differences between the PG and control groups at 14 days similarly did not attain statistical significance. The results suggest that in wound healing, the administration of di-MPGE2 may be beneficial during the early stages of inflammation, rather than during the later stages of remodelling.

Oxidative stress as a mechanism of cardiac failure in chronic volume overload in canine model.

We investigated the effects of chronic volume overload in the absence or presence of vitamin E supplements on the cardiac function and contractility, cardiac malondialdehyde (MDA)--a lipid peroxidation product--cardiac antioxidant enzyme activity and antioxidant reserve in canine model. The dogs were divided into three groups of seven dogs each: group I, control; group II, mitral regurgitation (MR) of 4 months duration; and group III, MR of 4 months duration receiving vitamin E (40 U/kg/daily) orally. MR was created by detaching two or more chordae tendinae to raise left atrial pressure to 2.5 to three times normal. MR produced a decrease in the index of myocardial contractility with little change in myocardial function. Decrease in myocardial (left and right ventricles) contractility was associated with an increase in cardiac MDA, and a decrease in cardiac antioxidant reserve and antioxidant enzyme activity. Prevention of volume overload-induced decrease in myocardial contractility by vitamin E was associated with a decrease in cardiac MDA and an increase in cardiac antioxidant reserve and glutathione peroxidase activity towards control levels. Superoxide dismutase and catalase activity remained depressed in vitamin E-treated group. The results indicate that chronic volume overload decreases the contractility of both right and left ventricles and is associated with oxidative stress in both ventricles. These results support the hypothesis that oxygen free radicals are involved in the chronic volume overload-induced cardiac depression.

Anaesthesia for coronary artery bypass surgery supplemented with subarachnoid bupivacaine and morphine: a report of 18 cases.

We report our experience with general anaesthesia (GA) supplemented with subarachnoid bupivacaine and morphine for coronary artery bypass surgery (CABG) in 18 patients. Fifteen patients were male, and mean age was 62 yr. Anaesthesia (GA) was induced with alfentanil 97 +/- 22 micrograms.kg-1 and midazolam 0.04 +/- 0.02 mg.kg-1 supplemented with a muscle relaxant, and maintained with isoflurane (0.25-0.5%) in oxygen throughout surgery. Spinal anaesthesia (SA) was then performed at a lumber level using hyperbaric bupivacaine (23-30 mg) and/or lidocaine (150 mg) with morphine (0.5-1 mg). Pooled data showed the following haemodynamic results (P < 0.05). Induction of GA produced a decrease in mean arterial pressure (MAP). Addition of SA produced a decrease in heart rate. Heart rate and MAP did not change with sternotomy. Phenylephrine support of arterial blood pressure was used at some time during operation in 17 patients. Supplementation of GA was minimal. Patients received 2.7 +/- 0.7 coronary grafts. Operating room time was 3.9 +/- 0.6 hr. Postoperative analgesic requirements were minimal, and in half of the patients tracheal extubation occurred on the day of surgery. Complications included one myocardial infarction, one resternotomy, a metabolic encephalopathy in a dialysis-dependent patient, and one case of herpes labialis. No patient recalled intraoperative events. Combined GA with SA may be an effective technique for CABG surgery. Further study of the cardiovascular, neurological and metabolic effects of the technique is required.

Management of a post-traumatic tracheo-esophageal fistula following failed primary repair.

Tracheo-esophageal (T-E) fistulas secondary to blunt chest trauma are extremely uncommon. Once the diagnosis is confirmed, surgical correction is indicated as spontaneous healing rarely occurs. Should a barium esophagram demonstrate a persistent T-E fistula postoperatively, we suggest that in the absence of clinical or radiological evidence of mediastinal or pulmonary infection, a conservative treatment regimen may be considered in an attempt to resolve the fistula without surgical intervention. Conservative management should be abandoned and surgery indicated if mediastinitis or recurrent aspiration pneumonias occur, or the fistula fails to heal within a four to six week period.

Very brief transient ischemic attack.

TIA is an important risk factor for ischemic stroke. Early diagnosis and management can result in a significant reduction in the risk of subsequent stroke. We report the case of a 54-year-old man who developed a 5-second episode of leg weakness and in whom a tight stenosis of the appropriate carotid artery was found. TIAs can sometimes be brief and have an atypical presentation, requiring a high level of suspicion for early diagnosis.

Oxygen free radicals in volume overload heart failure.

It has been suggested that oxygen free radicals (OFR) depress the excitation-contraction coupling in cardiac muscle. It is possible that a decrease in the cardiac contractility in the failing heart may be due to an increased OFR producing activity of polymorphonuclear (PMN) leukocytes. We studied the OFR producing activity (chemiluminescence) of PMN leukocytes from blood in dogs with heart failure due to chronic volume overload. The animals were divided into two groups: I) normal, (n = 10): II) dogs with mitral insufficiency (MI) of 6 to 9 months duration, (n = 10). Hemodynamic studies were done to establish the presence of heart failure. Blood samples were collected to measure PMN leukocyte chemiluminescence. There was a decrease in the cardiac index and index of myocardial contractility (dp/dt/IIP) and an increase in the left ventricular end-diastolic pressure in dogs with MI indicating left ventricular failure. The peak chemiluminescent activity of the PMN leukocytes in blood of dogs with failure was about four folds greater than that in the blood from normal dogs. These results suggest that there may be an increased OFR generation in dogs with volume overload heart failure. The decrease in the myocardial contractility in the failing heart might be due to an increase in the OFR produced by the PMN leukocytes.

Increased oxygen free radical activity in patients on cardiopulmonary bypass undergoing aortocoronary bypass surgery.

Cardiac dysfunction after cardiopulmonary bypass (CPB) has been reported by various investigators. Oxygen free radicals have been shown to depress cardiac function and contractility. To evaluate the possible role of oxygen free radicals (OFR) in post-pump cardiac dysfunction, measurements of cardiac function, OFR producing activity of polymorphonuclear (PMN) leukocytes (PMN chemiluminescence) and malondialdehyde (MDA), a lipid peroxidation product, in blood were made at induction of anesthesia (T1), before cross clamping of the aorta (T2), after closure of the chest (T3), and 24 hours postoperatively (T4) in 21 patients undergoing aortocoronary bypass surgery. The total OFR-derived chemiluminescence at T1, T2, T3, and T4 was 1590 +/- 156, 3169 +/- 338, 1972 +/- 214, and 2614 +/- 366 mv.min.10(6) PMN-1, respectively. Superoxide dismutase (SOD)-inhibitable chemiluminescence at T1, T2, T3, and T4 was 1214 +/- 129, 2674 +/- 328, 1752 +/- 215, and 2139 +/- 292 mv.min.10(6) PMN-1, respectively. Superoxide anion at T1, T2, T3, and T4 was 0.99 +/- 0.14, 1.30 +/- 0.17, 1.07 +/- 0.14, and 1.19 +/- 0.12 nmol.10(6) PMN-1.30 min-1, respectively. Blood MDA at T1, T2, T3, and T4 was 0.17 +/- 0.02, 0.25 +/- 0.03, 0.20 +/- 0.03, and 0.23 +/- 0.02 nmol/ml, respectively. OFR-derived and SOD inhibitable chemiluminescence, superoxide anion, and blood MDA increased significantly during CPB and postoperatively. There were decreases in the blood pressure and stroke volume, and increases in the central venous pressure, capillary wedge pressure, and heart rate during CPB and postoperatively. Cardiac output remained unchanged during this procedure. There was leukopenia during CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Disopyramide as a negative inotrope in obstructive cardiomyopathy in children.

Two children with left ventricular outflow tract obstruction due to myocardial hypertrophy received oral disopyramide as a negative inotrope. Both showed rapid improvement in clinical signs and by echo Doppler examination. Nearly complete abolition of severe left ventricular outflow tract obstruction was documented in each case. This experience may prompt further application of disopyramide as a therapeutic agent to relieve dynamic muscular subaortic obstruction in children.

Cardiac tamponade by loculated pericardial hematoma following open heart surgery: diagnosis by transesophageal echocardiography.

Loculated pericardial hematoma following open heart surgery may cause significant hemodynamic compromise. Recognition of this entity may be delayed because of the absence of the classical signs of cardiac tamponade. A 54-year-old woman is described in whom transesophageal echocardiography allowed rapid diagnosis of right atrial compression by a pericardial hematoma, following mitral valve replacement. Transesophageal echocardiography should be considered for the detection of posterior loculated pericardial hematoma in the hypotensive cardiac surgical patient with a suboptimal transthoracic echocardiogram.