Evaluation of reconstructive techniques of oropharyngeal defects.

Despite recent advances in radiation therapy and chemotherapy, surgical procedures remain the primary modality of head and neck cancer therapy. Adequate surgical resection frequently requires the removal of significant amounts of tissue. The primary concern of the reconstructive surgeon is the restoration of a functional aerodigestive tract. In addition to the prolongation of life, the quality of that life should be taken into consideration. The records of 25 patients undergoing oropharyngeal reconstruction for tumors stage 3 or 4 in the 4-year period from 1983 to 1986 were reviewed. After surgical extirpation, reconstruction was performed using either a pectoralis major musculocutaneous flap or a microvascular free flap. Results were evaluated with emphasis on both the intraoperative and postoperative course. The length of the procedure, time of initiation of oral feedings, time of decannulation, postoperative complications, time of discharge, and quality of life after discharge were considered. Those patients reconstructed with microvascular free flaps were able to tolerate oral feedings sooner and were discharged sooner than those patients reconstructed with pectoralis musculocutaneous flaps. In addition, the patients with pectoralis flaps were twice as likely to have local complications (e.g., superficial wound infection, fistula) as those with free flaps. The quality of the patient's life with respect to deglutition and intelligibility of speech was likewise better for those patients reconstructed with microvascular free flaps. The explanation of these results is presented.

Anatomic reconstruction and functional rehabilitation of oromandibular defects with rigid internal fixation.

Fifteen consecutive patients undergoing extensive surgery for head and neck cancer involving the oral cavity and oropharynx were reconstructed using the technique of rigid internal fixation combined with various vascularized flaps. The follow-up ranged from 6 to 18 months. Modifications in various myocutaneous or vascularized free flaps combined with an analysis of the radiation physics necessary to make this procedure a viable alternative for immediate and delayed mandibular reconstruction will be discussed. Consistently satisfactory functional and cosmetic results have been achieved.

Fluid shifts with successive running and bicycling performance.

Seven men and five women triathletes ran 10 km and bicycled 40 km at race pace for the purpose of studying changes in plasma, blood, and red blood cell volumes. A second trial followed 1 wk later with the order of exercise counterbalanced (running first-cycling second; cycling first-running second). Water consumption was measured by providing water bottles on the bike phase, at 3.2 and 6.7 km on the run phase, and at the transition area. Body weight was obtained at the start and end of each phase. A 10-ml blood sample was obtained just before starting and immediately upon finishing each phase. Changes in plasma volume, blood volume, and red cell volume were calculated from hematocrit and hemoglobin values. Changes in blood volume, plasma volume, and red cell volume did not differ between the sexes; therefore, results were combined. Sequential cycling and running caused significant hemoconcentration (-6 to -8% blood volume; -8 to -10% plasma volume) with moderate dehydration (-3 to -4% body weight) despite ad libitum fluid replacement. More severe fluid compartment shifts occurred on the initial phase regardless of exercise mode. Blood volume and plasma volume changes during the second mode of exercise were minor in extent with the major differences occurring in red cell volume. When fluid changes were calculated on a per hour basis, shifts were greater during running than during cycling.

Cardiac complications of suspension laryngoscopy. Fact or fiction?

A nonselective, prospective study of 100 consecutive patients undergoing suspension laryngoscopy was undertaken to observe the cardiac ischemic changes related to pharyngeal and laryngeal manipulation. Blood pressure, heart rate, rhythm, and cardiac response were monitored before, during, and after surgery. No significant changes were observed in normal, hypertensive, or high-risk patients. These findings differ from those previously reported.

Biogenic amine/metabolite response during in-flight emergencies.

Urine excretion of epinephrine (E), norepinephrine (NE), dopamine (DA), serotonin (5HT) and the metabolites vanillylmandelic acid (VMA), 4-hydroxy-3 methoxyphenylglycol (MHPG), homovanillic acid (HVA), 3, 4-dihydroxyphenylacetic acid (DOPAC), and 5-hydroxyindoleacetic acid (5-HIAA) was determined for students (n = 19) and instructors (n = 21) involved in flying training in-flight emergencies. Timed urine samples were analyzed using high-performance liquid chromatography with electrochemical detection. Basal excretion rates were determined at a later date. Four indices showed significant alteration during the emergencies. Epinephrine and the sum of epinephrine plus norepinephrine increased, the ratio dopamine/norepinephrine decreased and the ratio norepinephrine/serotonin increased. Instructors and students differed only in that VMA and the sum VMA plus MHPG were higher in students. Among the emergencies monitored, smoke and fumes in the cockpit and mechanical problems caused the greatest stress responses.

Physiological responses to a 20-mile run under three fluid replacement treatments.

Ten experienced male marathon runners ran 20 miles (32.18 km) on an outdoor course in a warm climate to measure responses in selected physiological variables as a result of drinking water, an electrolyte-glucose solution (ERG), or a caffeine solution (5 mg X kg-1 body weight) before and during the run. The caffeine solution and water were colored and flavored to resemble the electrolyte-glucose solution so that a double-blind condition could be maintained. Subjects ingested a different fluid in each of the three trials in a counterbalanced design. Parameters studied were: heart rate; rectal temperature; body weight; hemoglobin and hematocrit; serum glucose, sodium, potassium, chloride, and free fatty acids; perceived exertion; respiratory exchange ratio (R); and fractional utilization of VO2max (percentage of VO2max). Both R and percentage of VO2max were higher in subjects who drank the caffeine solution compared to those who drank water. Although post-run free fatty acid mean values were significantly higher than pre-run levels, there were no statistically significant differences among the fluid treatments. Since no other differences were observed, we concluded that, under the outdoor road-running conditions encountered here, these fluid replacement treatments did not differ in their effects on the parameters studied.

Hematological changes following a marathon race in male and female runners.

The subjects of this experiment were well-trained men (6) and women (4) participating in a marathon race in Phoenix, Arizona, on a cool, cloudy, windy day. Venous blood was collected one week prior to the run, immediately after, and 4, 8, and 24 h after the race. There were no significant changes in hematocrit, hemoglobin, or red blood cell counts following the race. The sample collected immediately after the race showed a pronounced leucocytosis. Differential counts showed that this increase in white blood cell count was limited to polymorphonuclear cells, suggesting that an inflammatory response to stress of the race was involved. Percentage changes in blood volume, red blood cell volume, and plasma volume were calculated from hematocrit and hemoglobin changes. These changes showed that there was reduction of plasma volume of 8% for females and 13% for males immediately after the race, with return to initial values within 8 h. We suggest that the increase in protein following the race was contributed by the flow of lymph from muscle to the vascular compartment.

Citrate uptake in membrane vesicles of Klebsiella aerogenes.

In whole cells of Klebsiella aerogenes grown anaerobically on citrate as sole carbon source, citrate uptake is followed by rapid catabolism of the substrate via the inducible citrate fermentation pathway. Membrane vesicles prepared from such cells take up citrate but do not catabolize it. Vesicles process d-lactate dehydrogenase and the Na+-requiring oxalacetate decarboxylase. Citrate is taken up in the presence of Na+, and other monovalent cations, such as NH4+, Rb+, Cs+, or K+, do not substitute for Na+. Li+ appears to act synergistically with Na+. Citrate uptake is inhibited by N-2, cyanide, azide, sulfhydryl reagents, dinitrophenol, fluorcitrate, and hydroxycitrate.

Enzymatic analysis of the requirement for sodium in aerobic growth of Salmonella typhimurium on citrate.

Na(+) was required for the aerobic growth of Salmonella typhimurium on citrate, but not on l-malate, glucose, or glycerol. The maximal growth rate and the maximal total growth occurred with 6 to 7 mm Na(+). Na(+) could not be replaced by K(+), NH(4) (+), Li(+), Rb(+), or Cs(+). Sonically treated extracts of citrate-grown cells contained the enzymes of the citrate fermentation pathway (citritase and oxalacetate decarboxylase) and all of the enzymes of the citric acid cycle. Thus, two separate routes of citrate catabolism appeared to be operational in the cells. Two discrete oxalacetate (OAA) decarboxylases were also demonstrated. One was of the "classic" type, being activated by Mn(++) and inhibited by ethylenediaminetetracetate (EDTA). It was present in the cell sap. The second decarboxylase closely resembled the Na(+)-activated OAA decarboxylase of citrate-grown Aerobacter aerogenes, whose growth also requires, or is increased, by Na(+). This decarboxylase was EDTA-insensitive, specifically activated by Na(+) and inhibited by avidin, and it had a high affinity for OAA. It was induced by growth on citrate, but not l-malate or glycerol. It is suggested that the Na(+) requirement for growth reflects the need to activate this OAA decarboxylase as a component of the citrate fermentation pathway and that citrate catabolism via the citric acid cycle, which should be independent of Na(+), is somehow dependent upon the activity of the Na(+)-activated enzyme.

Role of sodium in determining alternate pathways of aerobic citrate catabolism in Aerobacter aerogenes.

In contrast to the absolute Na(+) requirement for anaerobic growth of Aerobacter aerogenes on citrate as sole carbon source, aerobic growth of this microorganism did not require the presence of Na(+). However, Na(+) (optimal concentration, 10 mm) did increase the maximal amount of aerobic growth by 60%, even though it did not change the rate of growth. This increase in growth was specifically affected by Na(+), which could not be replaced by K(+), NH(4) (+), Li(+), Rb(+), or Cs(+). Enzyme profiles were determined in A. aerogenes cells grown aerobically on citrate in media of varying cationic composition. Cells grown in Na(+)-free medium possessed all the enzymes of the citric acid cycle including alpha-ketoglutarate dehydrogenase, which is repressed by anaerobic conditions of growth. The enzymes of the anaerobic citrate fermentation pathway, citritase and oxalacetate decarboxylase, were also present in these cells, but this pathway of citrate catabolism was effectively blocked by the absence of Na(+), which is essential for the activation of the oxalacetate decarboxylase step. Thus, in Na(+)-free medium, aerobic citrate catabolism proceeded solely via the citric acid cycle. Addition of 10 mm Na(+) to the aerobic citrate medium resulted in the activation of oxalacetate decarboxylase and the repression of alpha-ketoglutarate dehydrogenase, thereby diverting citrate catabolism from the (aerobic) citric acid cycle mechanism to the fermentation mechanism characteristic of anaerobic growth. The further addition of 2% potassium acetate to the medium caused repression of citritase and derepression of alpha-ketoglutarate dehydrogenase, switching citrate catabolism back into the citric acid cycle.

Requirement for sodium in the anaerobic growth of Aerobacter aerogenes on citrate.

Anaerobic growth of Aerobacter aerogenes on citrate as a carbon source required the presence of Na(+). The growth rate increased with increasing Na(+) concentration and was optimal at 0.10 m Na(+). The requirement was specific for Na(+), which could not be replaced by K(+), NH(4) (+), Li(+), Rb(+), or Cs(+). K(+) was required for growth in the presence of Na(+), the optimal K(+) concentration being 0.15 mm. Enzyme profiles were determined on cells grown in three different media: (i) intermediate Na(+), high K(+) concentration, (ii) high Na(+), high K(+) concentration, and (c) high Na(+), low K(+) concentration. All cells contained the enzymes of the citrate fermentation pathway, namely, citritase and the Na(+)-requiring oxalacetate (OAA) decarboxylase. All of the enzymes of the citric acid cycle were present, except alpha-ketoglutarate dehydrogenase which could not be detected. The incomplete citric acid cycle was, in effect, converted into two biosynthetic pathways leading to glutamate and succinate, respectively. The specific activities of citritase and OAA decarboxylase were lowest in medium (i), and under these conditions the activity of OAA decarboxylase appeared to be limited in vivo by the availability of Na(+). Failure of A. aerogenes to grow anaerobically on citrate in the absence of Na(+) can be explained at the enzymatic level by the Na(+) requirement of the OAA decarboxylase step of the citrate fermentation pathway and by the absence of an alternate pathway of citrate catabolism.

Oxidation D-malic and beta-alkylmalic acids wild-type and mutant strains of Salmonella typhimurium and by Aerobacter aerogenes.

A mutant strain of Salmonella typhimurium (SL 1634 dml-51) capable of growth on d-malate as sole carbon source was shown to produce d-malic enzyme. This enzyme was absent in the parent wild-type strain which was unable to grow on d-malate. Growth of the mutant on d-malate also resulted in a greatly increased level of beta-isopropylmalic enzyme compared with its level in the wild-type strain grown on citrate or l-malate. The d-malic and beta-isopropylmalic enzymes, both of which catalyze a nicotinamide adenine dinucleotide- and Mg(++)-dependent oxidative decarboxylation of their respective substrates, were shown to be distinct enzymes by selective inhibition with erythro-dl-beta-hydroxyaspartate and by other methods. Cell extracts of the mutant strain also oxidized dl-beta-methyl-, dl-beta-ethyl-, dl-beta-propyl- and dl-betabeta-dimethylmalates, in order of decreasing activity. dl-beta-Methyl-malate was shown to be oxidized by both the d-malic and the beta-isopropylmalic enzymes, whereas the oxidation of the other beta-alkylmalates appeared to be effected exclusively by the beta-isopropylmalic enzyme. beta-Isopropylmalic enzyme activity was induced by d-malate but not by l-malate, showing that it behaved as a d-malictype enzyme. Growth of Aerobacter aerogenes on d-malate, which caused induction of d malic enzyme, resulted in only a small increase in the activity of beta-isopropylmalic enzyme.