A triply templated artificial beta-sheet.

This paper describes the design, synthesis, and structural evaluation of a compound (4) comprising three molecular templates and a peptide strand that mimics a three-stranded protein beta-sheet. Two of the templates mimic the hydrogen-bonding functionality of peptide beta-strands and serve as the top and bottom strands by embracing the peptide strand, which is located in the middle of the sheet. The remaining template holds the three strands next to each other. The synthesis of artificial beta-sheet 4 begins with the bottom template and involves the sequential addition of the middle and top strands. (1)H NMR chemical shift and NOE studies establish that this compound folds to adopt a hydrogen-bonded beta-sheetlike structure in CDCl(3) solution. Chemical shift studies indicate that triply stranded artificial beta-sheet 4 is more tightly folded than its smaller doubly stranded homologue, artificial beta-sheet 1.

Pelvic lymphangioleiomyomatosis. Atypical precursor to pulmonary disease.

A 22-year-old woman presented with left pelvic pain and mass. Ultrasonography confirmed a multilocular left adnexal mass containing cysts of varying sizes. The patient had no pulmonary symptoms at the time of presentation. The mass was surgically excised and pathologic diagnosis of lymphangioleiomyomatosis (LAM) was made. Subsequently, she developed hemoptysis and pleural effusion. High-resolution computed tomography of the chest showed findings consistent with LAM. Early diagnosis and treatment for LAM was possible in this atypical case.

Acquired immunodeficiency syndrome among adolescents. Case surveillance profiles in New York City and the rest of the United States.

Adolescents engaging in certain sexual or drug-related behavior are at risk of contracting the human immunodeficiency virus infection in endemic locales. Local and national surveillance data were analyzed to determine the characteristics of the acquired immunodeficiency syndrome (AIDS) epidemic on adolescents. Of the 605 cases of AIDS in people aged 13 to 21 years reported through 1987, 518 were males (83 from New York City [NYC], NY), and 87 were females (28 from NYC). Over half of all adolescent males with AIDS reported homosexual contact. Transfusion/blood product-related human immunodeficiency virus acquisitions (especially in males with hemophilia) represented 11% of adolescent cases from NYC (1% of NYC adults) and 22% of adolescent cases in the United States (US) outside of NYC (4% of adults in the US). Intravenous drug use was more frequently reported among adolescents with AIDS from NYC (23%) than among adolescents outside NYC (14%). In females, heterosexual transmission accounts for about half of all adolescent AIDS cases and 29% of all adult cases. Age-appropriate services and behavioral interventions are urgently needed for high-risk adolescents.

Swing phase control with knee friction in juvenile amputees.

Above-knee amputees have a slower than normal walking velocity. In conventional prostheses the solution has been to apply knee friction to attempt to match the cadence of the prosthetic limb to the sound limb. Using kinematic data, we investigated the effect of variable knee friction on the swing phase of gait in juvenile amputees. The subjects were instructed to walk at a comfortable pace and were tested repeatedly with varying amounts of knee friction. We found that the excursion of the prosthetic shank as measured by knee range of motion was altered by changing the amount of knee friction. The period of the prosthetic shank remained constant when measured as a physical pendulum and when measured dynamically during gait. Therefore, knee friction is an effective means of providing the amputee with a more symmetrical appearing gait by matching the heel rise of the prosthetic limb to the sound limb. It is not an effective means, however, of matching the cadence of the prosthetic limb to the sound limb.

Coughs cause systemic blood flow.

Although it is known that rhythmic coughing can preserve consciousness during ventricular fibrillation, the arterial pressure transients which result have not yet been shown to reflect forward blood flow in man. The effectiveness of cough in causing forward flow in eight normal volunteers with bradycardia was studied. They coughed between cardiac cycles, using an audio and visual display of the electrocardiogram. The force of the cough was varied and measured with an oesophageal balloon. Blood flow was recorded with a Döppler velocity probe over the radial artery and a finger or ear photoplethysmograph. Motion artefact on the Döppler record due to coughing was excluded by transiently obstructing the brachial artery. We compared the areas under 5-10 consecutive Döppler and photoplethysmograph pulse flow tracings due to the cough and heart beat with those due to the immediately preceding heart beat alone. They were significantly increased. This augmentation was greater in those flow pulses accompanied by a more vigorous cough. It is concluded that coughing is associated with an effort dependent forward flow pulse in the arterial circulation.

Partial foot amputations in children. A comparison of the several types with the Syme amputation.

We compared the results in fourteen children in whom part of the foot was amputated with the results in a similar group of patients who had a Syme amputation. Based on levels of activity, physical examination, prosthetic requirements, ratio of the length of the fore part of the foot to the hind part, and gait mechanics, we classified the children into three groups. In Group I (patients with a metatarsal ray or transmetatarsal amputation) the results were clearly superior to those in the group with Syme amputation. In Group II (patients with a Lisfranc, mid-tarsal, or Chopart amputation and no equinus contracture) the patients had better over-all function but needed to make greater adjustments for gait than did those with a Syme amputation. In Group III (patients with a Chopart amputation who had an equinus contracture and inadequate length of the fore part of the foot) the results were clearly inferior to those of patients with a Syme amputation.

Effects of positive end-expiratory pressure on intracranial pressure in dogs with intracranial hypertension.

Positive end-expiratory pressure (PEEP) is used to improve oxygenation in patients with the adult respiratory distress syndrome. Nevertheless, this treatment may increase intracranial pressure (ICP) and be detrimental to certain neurosurgical patients. This clinical situation was simulated by administering PEEP to dogs with normal and elevated ICP. Increases in PEEP increased ICP in all animals. However, the presence of intracranial hypertension diminished the increase in ICP seen at a given level of PEEP. Cerebral perfusion pressure also fell less in the presence of intracranial hypertension than it did in the absence, although in the former situation cerebral perfusion pressure was at the lower limits of the range of cerebral autoregulation. These findings suggest that PEEP is no more detrimental to patients with elevated ICP than it is to patients whose ICP is normal, assuming that their cerebral autoregulation is not impaired.

New developments in cardiopulmonary resuscitation.

The traditional concept of cardiopulmonary resuscitation (CPR) is that the heart is squeezed between the sternum and the spine during external cardiac massage to create a pressure gradient that forces blood from the heart to the periphery. Although the heart may actually be squeezed in some persons by this maneuver, a newer view of CPR holds that closed-chest compression produces a generalized rise in intrathoracic pressure that is applied to the pulmonary vascular bed as well as the heart. Thus, the heart does not serve primarily as a pump during external cardiac massage but instead acts as a conduit for blood from the lungs. Furthermore, flow into extrathoracic vessels depends on their tendency to remain open or to collapse: forward flow occurs across the head during CPR because a pressure gradient is developed between the carotid artery and the more compressible jugular vein. These ideas have potential clinical implications and greatly increase our understanding of the physiology of CPR.

The effects of trochanteric epiphyseodesis on growth of the proximal end of the femur following necrosis of the capital femoral epiphysis.

Avascular necrosis of the hip was evaluated in two groups of patients. On group had sustained the insult to the epiphysis in infancy and had a mean growth loss in the proximal end of the femur of 21.5 millimeters at a mean age of 11.7 years. The other group had sustained the insult in mid-childhood (due to Legg-Perthes disease) and had a mean growth loss of seven millimeters at 12.4 years. Based on this evaluation, we concluded that trochanteric epiphyseodesis was nary in the latter group.

Prolonged respiratory paralysis in wound botulism.

Two patients had wound botulism with longer duration of respiratory paralysis than previously described. Each sustained extensive trauma to soft tissues and grossly contaminated wounds when thrown from a vehicle in a rural area. Progressive muscular weakness and respiratory distress occurred 8 and 13 days after injury, in the presence of infected wounds and clinical and laboratory findings characteristic of botulism. Spontaneous vital capacity and inspiratory effort served as bedside indicators of ventilatory function throughout 11 weeks of ventilatory support in each case and paralleled other clinical assessments of progress and recovery. Wound botulism may result in neuromuscular paralysis for a prolonged period. These cases illustrate the primary role of scrupulous nursing and respiratory care throughout such a period of ventilatory insufficiency.