The preservation of shoulder function after radical neck dissection

The most disabling side effect of radical neck dissection is the 'shoulder syndrome', caused by denervation of the trapezius muscle. This is due to division of the spinal accessory nerve, the motor nerve to the trapezius. Using cadaver dissections the anatomy of the cervical spinal nerve supply to the trapezius has been studied. At radical neck dissection stimulation of these cervical spinal nerves produced contraction of the trapezius muscle. Thus a modified technique of radical dissection has been developed preserving the cervical spinal nerves to the trapezius. Comparison of patients undergoing this modified radical neck dissection with patients undergoing a classical radical neck dissection shows them to have better shoulder function.

Crystallographic investigations of nicotinamide adenine dinucleotide binding to horse liver alcohol dehydrogenase

The binding of NAD to liver alcohol dehydrogenase has been studied in four different ternary complexes by using crystallographic methods. These complexes crystallize isomorphously in a triclinic crystal form which contains the whole dimer of the enzyme in the asymmetric unit. This form of the enzyme has been refined at 2.9-A resolution to a crystallographic R factor of 0.22. NAD binds in essentially the same way in these complexes. The binding site is located at the central part of the coenzyme binding domain. The adenine ring binds with hydrophobic interactions between two isoleucine side chains. Both ribose rings have 2E(C2'-endo) puckering, and each ribose makes three hydrogen bonds to the enzyme. The pyrophosphate bridge has hydrogen bonds to the side chains of arginine-47 and -369 and to main chain nitrogen atoms from the amino ends of two alpha-helices. The nicotinamide ring is in van der Waals contact with the active-site zinc atom and with the sulfur atoms of its cysteine ligands. The carboxamide group is about 30 degrees out of the plane of the nicotinamide ring and hydrogen bonds to main chain atoms of residues 292,317, and 319. The overall conformation of the NAD molecule is similar to that observed for other dehydrogenases, but differs in details. In the presence of the coenzyme, the enzyme undergoes a large conformational change from an open to a closed form. This conformational change has three major effects: to create favorable binding interactions with groups of the enzyme, to enclose the coenzyme and gain binding energy for the coenzyme by reducing the accessible surface area, and to close off one entrance to the active site. As a comparison, ADP-ribose binding has been studied in the open form of the enzyme. The adenosine moiety binds in a similar way as NAD, while the rest of the molecule has different interactions.

Structure of satellite tobacco necrosis virus after crystallographic refinement at 2.5 A resolution

The structure of the protein subunit of satellite tobacco necrosis virus has been solved at 3.7 A resolution. We have now crystallographically refined the original model and extended the resolution ot 2.5 A in order to get a model accurate enough to explain the details of the subunit interactions. The refinement was done with a novel method utilizing the icosahedral symmetry of the virus particle. The final model shows a complicated network of interactions, involving salt linkages, hydrogen bonds and hydrophobic contacts. In addition, we have located three different metal ion sites in the protein shell, linking the protein subunits together. These sites are probably occupied by calcium ions. One site is found in a general position near the icosahedral 3-fold axis of the virus. The ligands form an octahedral arrangement, with two main chain carbonyl oxygens (0-61 and 0-64), one carboxylate oxygen (OD1 from Asp194) of the same subunit and a second carboxylate oxygen (OE1 of Glu25) from a 3-fold related subunit. Two water molecules complete the octahedral arrangement. A second site is on the icosahedral 3-fold axis and is liganded by the carboxylate oxygens of the 3-fold related Asp55 residues. The third metal ion site is found on the 5-fold axis, liganded by the five carbonyl oxygens of Thr138 and two water molecules. We are unable to locate the first 11 N-terminal amino acid residues, which point into the virus interior. No interpretable density for RNA has been found, indicating that the nucleic acid of the virus does not have a unique orientation in the crystal.

The three-dimensional structure of retinol-binding protein

The complex of retinol with its carrier protein, retinol-binding protein (RBP) has been crystallized and its three-dimensional structure determined using X-ray crystallography. Its most striking feature is an eight-stranded up-and-down beta barrel core that completely encapsulates the retinol molecule. The retinol molecule lies along the axis of the barrel with the beta-ionone ring innermost and the tip of the isoprene tail close to the surface.

Structure, refinement, and function of carbonic anhydrase isozymes: refinement of human carbonic anhydrase I

The structure of human erythrocyte carbonic anhydrase I has been refined to a final R value of 19% to 2-A resolution by a combination of least squares refinement and model fitting in a three-dimensional graphics display. About 300 solvent atoms have been located bound to the protein molecule. An interesting hydrogen bond network involving Zn2+, the liganded solvent, side chain groups of Thr-199, Glu-106, Thr-7, and His-64 through two solvent molecules have been found that may be important for the catalytic mechanism of the carbonic anhydrase.

Effects of sequential periods of intracranial hypertension on lung fluid balance

Pulmonary hemodynamics and fluid and protein exchange were examined in dogs subjected to three successive periods of intracranial hypertension. Results indicate that the alteration in lung fluid balance is due to increased microvascular surface area following capillary recruitment. The relationship to the mechanism of neurogenic pulmonary edema is discussed.

Structural comparisons of some small spherical plant viruses

The structures of tomato bushy stunt virus, southern bean mosaic virus and satellite tobacco necrosis virus have been compared quantitatively. The organization of the shell domains of tomato bushy stunt virus and southern bean mosaic virus within the icosahedral envelope is identical. The wedge-shaped end of the subunit is closer to the fivefold or quasi-sixfold axes in all three viruses but the packing about the three- and twofold axes is quite different in satellite tobacco necrosis virus as compared to tomato bushy stunt virus or southern bean mosaic virus. The polypeptide folds of these viruses have greatest similarity in the beta-sheet region of the eight-stranded anti-parallel beta-barrel. The largest differences occur in the connecting segments. There is no clear indication of homologous amino acid sequences between southern bean mosaic virus and satellite tobacco necrosis virus. However, there is some conservation of the following functional groups. (1) Threonines and serines at the hexagonal-pentagonal wedge-shaped end of the subunit. (2) Lysines and arginines at the protein-RNA interface. (3) Hydrophobic residues in the cavity within the anti-parallel beta-barrel. (4) An aspartic acid near a site which binds Ca in tomato bushy stunt virus. (5) Ionic interactions in the contacts between fivefold-related subunits. These virus coat protein structures are not as similar to each other as the alpha and beta chains of hemoglobin but have greater likeness to one another than the NAD-binding domains of dehydrogenases or lysozymes from hen egg-white and T4 phage. The surface domains of tomato bushy stunt virus and southern bean mosaic virus are more like each other than like satellite tobacco necrosis virus. A divergent evolutionary tree is proposed on the basis of these observations.

Bone-conducted auditory stimulation in unrestrained, unanesthetized animals

A new method of eliciting auditory responses using bone-conducted stimuli was developed for use in freely-moving unanesthetized animals. In cats and rats piezoelectric materials were either bolted to or embedded within a dental acrylic skull platform. In order to produce acoustic stimulation, click and pip electrical waveforms were used to drive vibrations in the crystalline material. Responses to the crystal-elicited stimuli were compared with responses to air-coupled stimuli and were found to be virtually identical. Acoustic masking eliminated the response showing there is no significant contribution made to the responses by other sensory modalities.

Serotonin depletion prevents electrocortical synchronization following acute midbrain deactivation

Bilateral midbrain cooling (5-15 degrees C) was performed in cats pretreated with p-chlorophenylalanine (PCPA). This was done in order to examine the possible role of 5-hydroxytryptamine (5-HT) systems in the process of electrocortical synchronization which normally accompanies midbrain reticular deactivation. Prior to treatment with PCPA, midbrain cooling always produced tonic electrocortical synchronization and behavioral unresponsiveness. Cooling following PCPA treatment on the other hand produced behavioral unresponsiveness which was not accompanied by tonic electrocortical synchronization; in that case electrocortical desynchronization persisted in spite of midbrain reticular deactivation. These results lead to the hypothesis that two distinct, tonically active, desynchronizing systems exist. During the acute blockade of the classical midbrain reticular activating system it is proposed that 5-HT systems normally operate to inhibit or otherwise prevent the expression of the second brain stem electrocortical desynchronizing mechanism. It is proposed, therefore, that 5-HT acts indirectly to produce electrocortical synchronization. In the absence of 5-HT, midbrain deactivation is not sufficient to guarantee synchronization is assured only when both desynchronizing systems are inactivated as would be the case in the acute cerveau isolé.

Effects of intracranial and left atrial hypertension on lung fluid balance in sheep

Elevation of intracranial pressure (ICP; 50-150 Torr) in sheep produces an increase in protein-rich lymph flow (QL) from the lung. This may be attributed to either microvascular permeability changes or increases in filtration surface area through recruitment. To eliminate increases in surface area, we recruited potential filtration beds by increasing left atrial pressure (Pla; 27-35 Torr) prior to elevating ICP in sheep anesthetized with pentobarbital sodium or halothane. Under these conditions, increased pulmonary microvascular permeability would be expected to produce an increased QL, lymphatic protein flux (CL), and plasma clearance of protein (CP). The results of ICP elevation following a period of steady-state Pla hypertension showed no such change in QL, CL or CP (n=8) compared with prior period of increased Pla. ICP elevation alone (n=6) produces a significant increase in CP manifested as an increase in QL (73%), with little change in the lymph-to-plasma ratio of protein concentration. These results suggest that a change in pulmonary microvascular surface area (not permeability) is the primary mechanism underlying increases in protein-rich QL following the elevation of ICP alone.

The effects of temperature and acute alcohol intoxication on brain stem auditory evoked potentials in the cat

The effects of core temperature changes (less than 1 degree C) and acute ethanol intoxication (100-400 mg%) on brain stem auditory evoked potentials in cats were studied independently--then together--to distinguish between a putative direct pharmacological action of ethanol on brain stem auditory neurons, as reflected in reported BAEP latency changes, and in indirect action of ethanol mediated through slight changes in central temperatures. The results suggest that the reported BAEP latency effects are attributable, largely if not entirely, to the second mechanism above. No significant temperature-independent BAEP latency alterations occurred at any sublethal blood ethanol concentration or in one dosage that subsequently proved fatal. These findings do not exclude a direct ethanol effect on brain stem auditory neurons but provide no evidence for a temperature-independent effect. Knowledge of secondary BAEP temperature effects associated with drug administration is crucial to proper interpretation of BAEPs in both experimental and clinical applications.

Crystal structure analysis of the tetragonal crystal form are preliminary molecular model of pig-heart citrate synthase

The crystal structure of pig heart citrate synthase was analyzed at 0.35-nm resolution. Chain tracing was possible and an initial molecular model constructed. The dimensions of the dimer molecule (located on a crystallographic diad) are 7.5 x 6.0 x 9.0 nm. The chain folding is characterized by the predominance of helices and the absence of sheet structure. The electron density accounts for 355 residues per monomer, so that about 80 residues must be disordered in the crystal. The disordered segment in probably N-terminal. The ordered part consists of two closely associated domains, a large domain with 300 residues and a C-terminal domain of 55 residues consisting of 3(anti)parallel helices. The large domain is built from 12 helical segments, some of which are buried in the interior of the molecule. Inhibitor binding studies with citrate and CoA revealed citrate binding sites but showed no electron density for CoA. It is suggested that CoA binds to the disordered, flexible N-terminal domain. Experiments of limited proteolysis with trypsin showed that under conditions a segment of Mr 9000 is cleaved off selectively. The remaining 35 000-Mr part is dimeric.

Crystallization, crystal structure analysis and atomic model of the complex formed by a human Fc fragment and fragment B of protein A from Staphylococcus aureus

Crystals of the complex formed by human Fc fragment and fragment B (FB) of protein A from Staphylococcus aureus were prepared and the crystal structure determined at high resolution by multiple isomorphous replacement. Phase were improved considerably by combining these phases with calculated phases from the Fc component. FB is a small globular protein built of three parallel helices arranged in a triangular array. It binds by the first two helices of Fc and is attached to segments of CH2 and CH3. The CH3 module is unchanged between complex and Fc fragment crystals, but CH2 changes its position slightly relative to CH3. In addition, the upper third of CH2 is disordered in the complex crystals. Possible sources of this disorder are discussed.

State mental health institutions in the next decade: illusions and reality

Rejecting assertions that state mental health institutions are dying, the authors describe current proposals conceringin future roles of institutions and put forward two postulates as the basis for successful change. They argue that new or different roles for state mental health institution can better be developed if there exists a statewide structure that can both promote and direct change, and if there is a regionally based statewide plan for change that has the support of state, regional, and local leaders. They give several examples of institutionally based service units that could be operated in concert with community services in a unified mental health system. They urge mental health administrators to admit the need for institutional change and to provide active leadership in bringing it about.

Angiographic aspects of experimental nonocclusive intestinal ischemic injury

An experiment was designed to fulfill the following aims: (1) to develop a model of nonocclusive intestinal ischemic injury compatible with survival for several days; (2) to determine the accuracy of angiography in diagnosing the presence and extent of intestinal ischemic injury; and (3) to determine the therapeutic and diagnostic value of intraarterial papaverine infusion. Experimental shock models were developed in the dog, and efficacy of the hypovolemic and normovolemic models was confirmed by gross and histologic evidence of intestinal injury in surviving dogs. No reliable angiographic signs of intestinal mucosal injury could be elicited. Angiographic abnormalities associated with the experiment were attributable to the shock itself and disappeared with the relief of shock. Infusion of papaverine into the superior mesenteric artery within 2 hr of the onset of shock prevented or ameliorated intestinal injury.

The National Health Planning Act: significance for mental health agencies

In examining the National Health Planning and Resources Development Act, the authors identify nine areas that have special meaning for those responsible for planning, administration, and delivery of mental health services. Believing that mental health planning can be done more effectively by mental health agencies, they recommend a series of steps that can be taken by mental health administrators to maintain responsibility for planning their programs while ensuring close coordination with general health planning activities. It is their conviction that mental health authorities should commit themselves to the planning process and put their commitment to work by recruiting knowledgeable and skilled planning staffs.