Neuromuscular organization of the pectoralis (pars thoracicus) of the pigeon (Columba livia): implications for motor control

The pectoralis (pars thoracicus) of the domestic pigeon (Columba livia) is divisible into two anatomical parts, the pars sternobrachialis (SB) and the pars thoracobrachialis (TB). Innervation to this complex is from rostral and caudal branches of the brachial ventral cord. In four anesthetized pigeons, the distribution of muscle units associated with each nerve branch was mapped after prolonged stimulation of each nerve and subsequent analysis for muscle fiber glycogen. An additional three animals were used to analyze the morphology, distribution, and histochemical profiles of the muscle fibers in the SB and TB subregions. Fibers were characterized on the basis of their reactions for myofibrillar adenosine triphosphates (alkaline and acid preincubation) and reduced nicotinamide adenine dinucleotide diaphorase (NADH-D). The SB is primarily innervated by the rostral nerve branch and the TB by the caudal nerve branch. For two-thirds of the muscle's length, the SB is separated from the TB by an aponeurosis, the membrana intermuscularis (MI). SB and TB fibers located posteroventral to the caudal margin of the MI are innervated variously by both nerves. Two populations of fibers were recognized, distinguishable primarily by 1) fiber diameter and 2) density of the NADH-D reaction product. Compared to the TB, the SB possesses a higher average percentage of large fibers. Within the SB but not the TB the percentage of large fibers increases from deep to superficial. These data support our previous findings that the pars thoracicus of the pigeon is partitioned into at least two functional subunits, each with a potential for independent action on the wing during flight.     

The effects of separation and reunion on the behavior of mother and infant squirrel monkeys

Mother and infant squirrel monkeys that lived together in a socially restricted environment were separated for a period of seven days after the infants had become relatively independent, and were then reunited. Behavioral observations before, during, and after separation indicated that (1) female infants became independent of their mothers earlier than males, (2) neither mothers nor infants were severely affected by separation, and (3) an increase in attachment occurred following reunion only when the mother had a limited history of maternal experience. These results suggest that (1) certain characteristics in the maternal behavior of the squirrel monkey facilitate readjustment in mothers and infants following maternal separation, (2) maternal experience can influence the mother-infant relationship following a period of separation, and (3) the independence of infants from their mothers may be a function of both sex and species.     

Human polymorphonuclear leukocyte interaction with cyclosporine A.

The effects of cyclosporin A (cyA) on human polymorphonuclear leukocyte function, including phagocytosis, its associated metabolic burst, bacterial killing, and chemotaxis, were evaluated. Both Pseudomonas aeruginosa and Staphylococcus aureus were used as test particles. Polymorphonuclear leukocytes incubated in 10 and 50 micrograms of cyA per ml behaved normally with respect to phagocytosis and hexose monophosphate shunt activity at both high (10:1) and low (2:1) S. aureus/leukocyte ratios. With a small bacterial inoculum, killing of S. aureus was slightly impaired at early times only in the presence of 50 micrograms of cyA per ml. Phagocytosis and killing of P. aeruginosa with both large and small bacterial inocula were unaffected by cyA. Chemotaxis was within normal limits under all conditions. In addition, polymorphonuclear leukocytes from four renal transplant recipients receiving both cyA and prednisone demonstrated normal metabolic bursts and bacterial killing with both small and large inocula of S. aureus.     

Differences in the mother-infant relations of squirrel monkeys housed in social and restricted environments

Mother and infant squirrel monkeys were housed together in either a group or a restricted environment until the infants were approximately 22 weeks of age. Observations of the mothers' and infants' behavior during this period revealed clear differences between the rearing conditions. Mothers in the socially restricted environment avoided and punished their infants more and were generally less protective than those in the group environment. However, these differences did not appear to reflect differences in maternal attitudes per se, but rather the extent to which infants in the two environments engaged in certain activities. Infants in the restricted environment attempted to play with their mother more often and remained closer to her as they became older.     

A continuing controversy: magnesium sulfate in the treatment of eclamptic seizures

It would appear from the above that Pritchard agrees with the use of some agents other than magnesium sulfate that have known anticonvulsant properties. We believe that the subject at issue is whether magnesium sulfate should be used in treating the seizures of eclampsia. In our "Controversies" article, we do not address the issue of whether magnesium sulfate modifies pathophysiological factors leading to preeclampsia, but restrict ourselves to the treatment of the seizure per se, once seizures supervene, and the avoidance of their recurrence. The pathophysiological mechanisms and optimal treatment of preeclampsia and of eclampsia (excepting seizures) remain to be determined, as does the use of magnesium sulfate in this condition. Eclamptic seizures are clinically and electroencephalographically indistinguishable from generalized tonic-clonic seizures. Whether seizures arise in or out of the setting of preeclampsia, they should be treated as are other seizures, with known anticonvulsants. Controlled clinical trials are needed to address the effectiveness of alternative antiseizure regimens.     

Recent advances in understanding the pathogenesis of the hemolytic uremic syndromes

One of the requirements for an agent to cause hemolytic uremic syndrome (HUS) is its ability to injure endothelial cells. Shiga-like toxin (SLT) can do this. SLT is produced byEscherichia coli andShigella dysenteriae serotype 1; both have been implicated as causes of typical HUS. Endothelial cells have receptors (GB₃) for SLT and the toxin can inhibit eukaryotic protein synthesis, thereby causing cell death. Glomerular endothelial cell injury or death results in a decreased glomerular filtration rate and many of the perturbations seen in HUS. It is no longer certain that hemolysis is the result of a microangiopathy. Cell injury results in release of von Willebrand multimers; if these are ultra-large, thrombosis may ensue. There is also increasing evidence that neutrophils have a role in the pathogenesis of typical HUS.Streptococcus pneumoniae can also cause HUS and care must be taken to avoid giving plasma to patients withS. pneumoniae-associated HUS. There is compelling evidence that types of HUS are inherited by autosomal recessive and autosomal dominant modes. Patients with autosomal recessive HUS may have recurrent episodes. Mortality and morbidity rates are high for the inherited forms.     

Professional associations and managed care. How four provider groups are helping their members

Managed care is facilitating rapid change in the day-to-day practice of many addiction treatment and mental health professionals. It is only natural, therefore, that the associations representing the various disciplines in behavioral healthcare should seek to present short- and long-term plans, advice, and programs for their members. We have asked leaders from four prominent groups to present what their organizations are doing today to assist professionals in adapting to the new realities of the healthcare system. The comments below are by no means conclusive, and are representative of a few efforts and thoughts. It is our mission at Behavioral Healthcare Tomorrow to provide an independent platform for dialogue in the world of mental health and addiction treatment. It is our hope that the proposals and ideas published here stimulate even more planning amongst providers as managed care assertively enters public sector services.     

Nabumetone in elderly patients with osteoarthritis: economic benefits versus ibuprofen alone or ibuprofen plus misoprostol

Nonsteroidal anti-inflammatory drugs (NSAIDs) vary in their potential to produce gastropathy. We compared the 3-month direct medical costs, including those associated with treating NSAID-induced adverse events, of nabumetone, ibuprofen, or ibuprofen plus misoprostol in 171 elderly patients with osteoarthritis. Total direct medical costs per patient treated were $US183 for nabumetone, $US252 for ibuprofen, and $US270 for ibuprofen plus misoprostol. Differences resulted from higher costs associated with treatment of drug-related adverse events with ibuprofen, and higher drug acquisition prices with the combination regimen. Sensitivity analyses demonstrated that direct costs with nabumetone approached those for the other 2 regimens if the price of nabumetone increased by 60%, the probability of lesion formation with nabumetone increased 4-fold, the probability of a lesion greater than 0.5cm being symptomatic and needing treatment was 31%, or the price of misoprostol decreased by 50%. Although this study found more lesions because of mandated endoscopies than might be recognised or treated in clinical practice, the results suggest an economic benefit of nabumetone.