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Cells respond to a myriad of stressors by senescing, acquiring stable growth arrest, morphologic and metabolic changes, and a senescence-associated-secretory-phenotype (SASP). The heterogeneity of senescent cells (SnCs) and their SASP is vast, yet poorly characterized. SnCs have diverse roles in health and disease and are therapeutically targetable, making characterization of SnCs and harmonization of their nomenclature a priority. The Cellular Senescence Network (SenNet), a NIH Common Fund initiative, will leverage emerging single cell and spatial-omics to identify and map SnCs in numerous organs across the lifespan of humans and mice. A common coordinate framework will integrate the data, using validated, standardized methods, creating public 4-dimensional SnC atlases. Key SenNet deliverables include development of innovative tools/technologies to detect SnCs, biomarker discovery, common annotations to describe SnCs and extensive public data sets. The goal is to comprehensively understand and map SnCs for diagnostic and therapeutic purposes to improve human health.

6078Background: Residual disease after concurrent chemoradiation in locally advanced Head and Neck cancer is typically contained in involved lymph nodes (LNs), with primary tumors (PTs) showing com...

During the last two decades, paleoanthropology has focused increasingly on the global issue of modern human origins, and a preeminent part of that process has concerned the fate of the Neandertals of the northwestern Old World. Not so long ago, working on the origins of modern humans was a niche cloaked in convenient obscurity. Many human paleontologists were content to largely ignore, and thus remained ignorant of, the hominid fossils of the later Pleistocene, an attitude parallel to that of Bordes regarding the Neolithic in comparison to the more glamorous Paleolithic; he referred to the former simply as, “C'est de la merde!” However, the Neandertais have become a topic guaranteed to attract attention, thus drawing in scholars who until recently disdained interest in such basically human fossil hominids. They are now willing to direct their students' and even their own research toward late archaic humans (such as Neandertals) and early modern humans in whatever portion of the Old World is most readily available.

This study was performed to determine whether the hypoglossal nerve (cranial nerve XII [XII]) would serve as a useful donor for laryngeal reinnervation by anastomosis to the recurrent laryngeal nerve (RLN). Twenty hemilarynges in 10 dogs were studied pro-spectively after XII-RLN anastomosis (group A; n = 5), split XII—RLN anastomosis (group B; n = 3), XII-RLN anastomosis with a 2-cm interposition graft (group C; n = 2), no treatment (group D; n = 5), RLN section (group E; n = 2), or ansa cervicalis—RLN anastomosis (group F; n = 3). Spontaneous activity was observed monthly by infraglottic examination through permanent tracheostomies and was recorded by electromyography. Laryngeal adductory pressure and induced phonation were obtained by stimulating the RLN while passing a pressure transducer balloon or humidified air through the glottis. At sacrifice, the laryngeal muscles were stained for adenosine triphosphatase to determine the ratio of type I to type II fibers. Retrograde labeling of the brain stem was performed with horseradish peroxidase. Infraglottic examination at 6 months showed a full range of adductory motion in groups A and B during the swallow reflex, comparable with that in group D. Groups C and F showed good bulk and tone, but little spontaneous motion. Group E remained paralyzed. Stimulation of the transferred nerves caused more activity in groups A and B than in the other groups; groups C and F partially adducted at high levels. The laryngeal adductory pressure responses of groups A and B were similar to those of group D. The XII-reinnervated larynges were capable of producing normal induced phonation. Retrograde labeling of the RLN showed that the reinnervating axons originated only in the hypoglossal nucleus. Electromyography of the reinnervated adductor muscles confirmed spontaneous activity in the dogs (awake). Histochemical analysis confirmed slow-to-fast transformation of both the posterior and lateral cricoarytenoid muscles, indicating that significant reinnervation occurred. We conclude that the hypoglossal nerve functions well as a donor for adductory reinnervation of the larynx.

Previous uncontrolled studies suggested a therapeutic benefit for treating gastroesophageal reflux disease (GERD) among patients with laryngitis. The present study is the first randomized, placebo-controlled, double-blind study of gastric acid suppression among patients with laryngitis in the United States.Patients diagnosed with idiopathic chronic laryngitis were randomized to receive either lansoprazole 30 mg p.o. b.i.d. or a matching placebo for 3 months. Before randomization, all patients underwent upper endoscopy, dual probe ambulatory 24-h esophageal pH-metry, and laryngoscopy, as well as completing a symptom questionnaire for GERD and laryngitis. The primary outcome of treatment was the complete resolution of laryngeal symptoms.A total of 22 patients with symptoms and signs of chronic laryngitis were enrolled, 20 of whom completed the study. At baseline, there were no significant differences between the two groups with regards to GERD symptoms, erosive esophagitis, proximal and distal esophageal pH-metry, or laryngeal signs and symptoms. In an intention-to-treat analysis, six patients in the lansoprazole group (50%) and only one patient (10%) in the placebo group achieved a complete symptomatic response, p = 0.04. Apart from receiving lansoprazole, there were no significant differences between responders and nonresponders in any of baseline esophageal or laryngeal signs and symptoms.Empirical treatment with lansoprazole is efficacious in relieving symptoms of laryngitis compared to placebo. Such treatment can be considered as a first-line option in managing patients with idiopathic chronic laryngitis.

OBJECTIVE The effect of incomplete antecedent injuries on subsequent facial nerve regeneration within cable graft repairs is not known. The purpose of this study is to compare facial nerve regeneration after an immediate and delayed neural cable graft repair. METHOD Rabbit facial nerve regeneration after complete transectional injuries of the buccal division was compared in two experimental models. In one, a 10-mm segment of the nerve was transected, rotated 180 degrees, and immediately repaired as a cable graft (N=8). In the second, a preliminary nerve crush was allowed to recover over a 4-week period and a 10-mm segment of nerve centered on the crush site was then transected, rotated 180 degrees, and delay repaired as a cable graft (N = 7). Data are presented as total numbers of regenerating myelinated axons that traverse the surgical repair to innervate the cable graft and distal nerve stumps, as well as the percentage of regenerating neurites compared with preoperative pooled and individual controls. Subpopulations of regenerating neurons are delineated to quantify the pattern of neural innervation. RESULTS Five weeks after cable graft repair both groups had similar myelinated outgrowth from the proximal nerve stump across the proximal anastomosis to innervate the cable graft (3995 +/- 1209 vs. 3284 +/- 651; P = .89). However, the delayed repair group had more intrafascicular regeneration within cable grafts (2261 +/- 931 vs. 1660 +/- 1169; P = .02) and distal nerve stump (1532 +/- 281 vs. 445 +/- 120; P = .004) than the immediate repair group. The immediate repair group had greater extrafascicular nerve regeneration in the cable graft (2335 +/- 1954 vs. 437 +/- 236; P = .001) and more myelin and axonal debris in pre-existing neural fascicles of the cable graft (P = .02) and distal nerve stump (463 +/- 187 vs. 103 +/- 87; P = .02). CONCLUSIONS Antecedent priming lesions do not enhance axonal survival as determined by regenerating myelinated axonal counts. However, antecedent injuries enhance the efficiency of neural innervation of the affected mimetic musculature by increasing the number of myelinated intrafascicular neural regenerants in the cable graft and distal nerve stump. This is accomplished by two factors: increased perineural fibrosis and decreased intrafascicular myelin and axonal debris.

Thrombin and serine protease inhibitors such as protease nexin-1 (PN-1) have been implicated in neurite outgrowth activity. We compared rat sciatic nerve regeneration in 10-mm silicone tubes, bridging an 8-mm nerve gap, that were prefilled with thrombin (1.5 IU) and PN-1 (50 micrograms/mL or 1 mg/mL) to those filled with saline solution (control). Neural regeneration and fibrinoid matrix progression (deposition of extracellular matrix) were analyzed at 1, 4, 17, and 21 days after silicone tube implantation. At 1 and 4 days after implantation, thrombin reduced fibrinoid matrix length propagation from both the proximal and distal transected nerve stumps, but PN-1 and saline did not interfere with matrix progression (p < .05). Seventeen days after implantation, the number of silicone tubes containing myelinated neuronal regenerates at the mid-tube region was 1 of 6 for thrombin, 6 of 9 for PN-1, and 6 of 10 for saline solution. Twenty-one days after implantation, 11 of 11 tubes with saline solution, 9 of 11 with PN-1 at 1 mg/mL, and 7 of 9 with PN-1 at 50 micrograms/mL had myelinated neural regenerates in the mid-silicone tube region, while only 2 of 9 thrombin-containing silicone tubes contained myelinated axons. There was no statistically significant difference in myelinated neurite regenerates at 17 and 21 days after implantation among silicone tubes prefilled with saline solution and PN-1 (50 micrograms/mL or 1 mg/mL). Thrombin interfered with matrix progression and significantly reduced the number of myelinated neurite regenerates (p = .01). The PN-1 and saline solutions did not inhibit matrix progression or affect the number of myelinated axonal regenerates (p = .92).

Pancreatic carcinoma is a rare cause of GI bleeding. We have studied eight patients in whom major digestive hemorrhage was the first sign of a subsequently proven pancreatic malignancy. Bleeding was characteristically severe and unremitting, including hematochezia (four), melena (three), and hematemesis (one). In seven cases, direct tumor invasion into a contiguous portion of the GI tract was present. Tumor erosion occurred into the third portion of the duodenum (three) descending duodenum (two), stomach (one), and transverse colon (one). In one patient, a metastatic bleeding lesion was present in the sigmoid colon. The four patients who required urgent laparotomy for control of major hemorrhage died during the initial hospitalization. Conventional diagnostic evaluation by endoscopic and roentgenographic techniques was commonly unsuccessful. Our retrospective analysis suggested that a more aggressive approach, including early angiography in unrelenting and undiagnosed bleeding, might have aided diagnosis and averted laparotomy in a population with dismal prospects for a surgical solution. Clinicians should be aware that pancreatic malignancy may present with a varying spectrum of GI bleeding ranging from occult to potentially exsanguinating hematemesis, hematochezia, or melena.

The creation of a portfolio documenting adults' experiences is gaining acceptance in higher education as well as in business and industry. We describe a critical first step in portfolio construction—the development of a folio of relevant materials documenting a person's learning.

Instructional methods and techniques that are consistent with the tenets of experiential learning and that can be used at in-class or field-based sites are described.

We describe a simple method to create a reusable and customizable dental guard using readily available materials. Our method does not require an extra patient visit and does not add operative time. Furthermore, our guard is rigid, which allows force to be distributed over adjacent teeth, unlike soft mouth guards.

Peripheral neural regeneration, over a 10-mm transectional gap, was determined in 70 rabbit buccal divisions of the facial nerve using two entubational systems (semipermeable and impermeable silicone chambers) prefilled with three natural occurring media (serum, blood, and saline) during a 5-week period. The number of myelinated axonal regenerates at the midchamber and at 2 mm in the distal transected neural stump were counted in each group and compared to pooled myelinated axonal counts in 9 normal rabbit buccal divisions of the facial nerve. Semipermeable porous chambers had an overall greater regeneration success rate (75% vs. 42.8%) and regained, on the average, a higher number of myelinated axons (51.4% vs. 26.1%) than silicone chamber regenerates. Semipermeable chambers prefilled with serum or blood had significantly higher regeneration success rates, myelinated axonal counts, and percentages of neural innervation of the distal transected neural stump. Both entubational systems produced similar axonal counts with intraluminal saline. The highest overall success rate (93.7%) and average number of myelinated axons per chamber (3072) were achieved in semipermeable chambers prefilled with serum. The greatest variability in myelinated axonal counts (0 to 3266 axons) and percentage of distal stump innervation (5.5% to 98.1%) was seen in silicone chambers filled with saline. The percentage of myelinated axons from the midchamber that innervated the distal stump was greater in semipermeable chambers with blood (73%) and serum (54%) than in silicone saline chambers (43%). On the average, the distal stumps from semipermeable chambers filled with serum (47%) and blood (33.5%) regained a higher percentage of normal myelinated axonal counts than silicone-saline chambers (12.5%). These results suggest that both the construction of entubational chamber and the intraluminal medium can have significant influence on neurite regeneration. Semipermeable chambers prefilled with serum have a strong neurite-promoting potential in peripheral neural regeneration of rabbit facial nerves.

(1991). Rethinking Utopia: From Metropolis to Batman. Rethinking Marxism: Vol. 4, No. 2, pp. 79-91.

Fossils are our most reliable guide to the organisms and environment of the past. We look at fossils from the most ancient epochs in history

Palaeontologists can decipher how ancient organisms lived and interacted using taphonomy, the study of how fossils form. Find out what they've discovered

Gastroesophageal reflux disease (GERD) is a proposed risk factor for developing laryngeal and pharyngeal cancers. No controlled study has examined this association.A case-control-study was performed using the computerized hospitalization and outpatient databases of the US Department of Veterans Affairs. All patients, who were veterans, had been identified as being hospitalized with laryngeal or pharyngeal during 1991 to 1997. In addition, all persons diagnosed with laryngeal or pharyngeal cancer in 1999 in the outpatient files were identified. From the same patient populations, four nonmatched control subjects were randomly assigned for each case. The medical history for cases and controls was retrospectively searched for GERD diagnoses, tobacco use, and alcohol dependence. Multivariable logistic regression analyses were performed to assess the risk factors for laryngeal and pharyngeal cancers.A total of 8,228 hospitalized patients with laryngeal cancers and 1,912 with pharyngeal cancers were compared to 32,912 and 7,648 hospitalized controls, while 9,292 outpatients with laryngeal cancer and 2,769 outpatients with pharyngeal cancer were compared with 37,168 and 11,076 outpatient controls without cancer. Among hospitalized persons, the prevalence of GERD was higher among patients with laryngeal cancer (8.9 vs 4.0%, p0.0001) and pharyngeal cancer (6.2 vs 3.8%, p0.0001). In a multivariable logistic regression analysis that was controlled for age, gender, ethnicity, smoking, and alcohol, GERD was associated with an adjusted odds ratio (OR) of 2.40 for laryngeal cancer among hospitalized patients (95% CI 2.15-2.69, p0.0001) and an adjusted OR of 2.38 (95% CI 1.87-3.02, p0.0001) for pharyngeal cancer. For outpatients, GERD was associated with an adjusted OR = 2.31 (95% CI 2.10-2.53) for laryngeal cancer and adjusted OR = 1.92 (95% CI 1.72-2.15).Among US veterans, the risk for laryngeal or pharyngeal cancers is modestly increased in the presence of GERD. This effect seems to be independent of age, gender, smoking, and alcohol intake.

A canine model was used to measure changes in laryngeal adductory pressure (LAP) following injections of vecuronium bromide, a short-acting neuromuscular blocking agent. At a constant volume, LAP was inversely related to the dose (and concentration) of vecuronium injected. At a constant dose (0.05 mg), LAP did not vary significantly over a wide range of injection volumes, from 0.05 to 0.50 mL. At a constant dose and volume, the site of injection was varied among the anterior, middle, and posterior vocal fold, the interarytenoid region, and the anterior contralateral vocal fold. Reduction in LAP was greatest (p < .05) for the posterior vocal fold injection site (78% reduction); less reduction was seen for the middle (54%) and anterior (52%) vocal fold and interarytenoid (43%) injection sites. These results have implications for laryngeal botulinum toxin injections, which are discussed.

The minimum number of regenerating facial nerve myelinated motor axons that are required to innervate and activate the mimetic musculature is not known. We compare rabbit facial nerve regeneration following complete transectional injuries of the buccal division to the evoked and behavioral muscle activities of the quadratus labii superioris muscle of the rabbit in three experimental models: end-to-end direct anastomosis (N = 4), 8-mm autologous nerve grafts (N = 8), and 10-mm silicone chamber implants (N = 40). Data are presented as total numbers of regenerating myelinated axons that traverse the surgical repair and innervate the fascicles of the transected distal nerve stump, as well as the percentage of regenerating neurites, as compared to the preoperative normal controls. Five weeks after neural repair, direct end-to-end anastomosis regained more myelinated axons across the reconstructed defect (2,632 × 1,232; 67%) than silicone tube implants (2,006 × 445; 51%) or autologous cable graft repairs (1,660 × 1,169; 42%). However, only a small percentage of myelinated fibers innervated the intrafascicular region of the distal transected neural stump in direct anastomosis (948 × 168; 24%), silicone tube implants (670 × 275; 17%), or autologous nerve grafts (445 × 120; 12%) in rabbits that regained evoked and behavioral mimetic muscle activity. All rabbits with direct anastomosis and neural cable grafts regained motor activity, despite the fact that 66% of regenerating motor neurites in cable graft repairs and 54% in direct anastomosis were collateral sprouts that did not contribute to effective muscle activity. In 17 rabbits with neural regenerates within the silicone tube implants that did not regain mimetic activity, the mean number of regenerating myelinated motor axons across the defect was 504 × 419 (13%), and the mean number of axons that innervated the distal transected nerve stump fascicles was 277 × 128 (7%). Therefore, the minimal number of motor axons that is required to activate the quadratus labii superioris muscle is 12% of the original motor axon population of the normal buccal nerve division.

Previous reports suggest that nerve growth factor (NGF) enhanced nerve regeneration in rabbit facial nerves. We compared rabbit facial nerve regeneration in 10-mm silicone tubes prefilled with NGF or cytochrome C (Cyt C), bridging an 8-mm nerve gap, to regeneration of 8-mm autologous nerve grafts. Three weeks following implantation, NGF-treated regenerates exhibited a more mature fascicular organization and more extensive neovascularization than Cyt C-treated controls. Morphometric analysis at the middle of the tube of 3- and 5-week regenerates revealed no significant difference in the mean number of myelinated or unmyelinated axons between NGF- and Cyt C-treated implants. However, when the numbers of myelinated fibers in 5-week regenerates were compared to those in their respective preoperative controls, NGF-treated regenerates had recovered a significantly greater percentage of myelinated axons than Cyt C-treated implants (46% versus 18%, respectively). The number of regenerating myelinated axons in the autologous nerve grafts at 5 weeks was significantly greater than the number of myelinated axons in the silicone tubes. However, in the nerve grafts the majority of the axons were found in the extrafascicular connective tissue (66%). The majority of these myelinated fibers did not find their way into the distal nerve stump. Thus, although the number of regenerating myelinated axons within the nerve grafts is greater than that of axons within silicone tube implants, functional recovery of autologous nerve graft repairs may not be superior to that of intubational repairs.

The last decade has seen dramatic improvements in techniques for retrieving DNA from ancient remains – whether petrified, frozen or mummified

Naive human T cells home to peripheral lymph nodes via the leukocyte endothelial cell adhesion molecule-1 (LECAM-1, l-selectin, CD62L, Leu8 antigen) they express. We enriched populations of CD4+CD62L+ cells (attachment of Leu8+ T cells to flasks coated with anti-mouse IgG (AIS); Leu8+ T cells, 82.3% pure (+/- 2.3%), enriched for CD4+ cells by incubation over flasks coated with anti-CD4 antibody--this 3-4-day procedure yields an 88 +/- 1.4% recovery. Cells were treated with dexamethasone in vitro for 24-48 h, and monitored by flow cytometry. We found severe toxicity by this steroid at high concentration (10(-6) M: 35% decrease in CD62L+ T cells, 22% drop specifically in CD4+CD62L+ cells), suggesting the onset of receptor-mediated apoptotic events. The toxicity was dose dependent (5% and 7% drop in CD62L+ T and CD4+CD62L+ cells, respectively, at 10(-9) M, the concentration found in plasma 10 h following the administration of 1 mg dexamethasone). One mg of dexamethasone given to normal subjects leads to a 15-20% decrease in circulating CD4+CD62L+ cells at 10 h. This tends to be correlated with a drop in the number of glucocorticoid cytosolic receptors. Thus, steroids seem to modulate CD4+CD62L+ cell homing by means of receptor-mediated mechanisms.

Previous reports suggest that nerve growth factor (NGF) enhanced significantly nerve regeneration in rabbit facial nerves (Chen et al.). We compared facial nerve regeneration in silastic tubes prefilled with NGF or cytochrome C (Cyt. C, control) to autologous neural grafts. A 10-mm silastic tube prefilled with a solution of either NGF or Cyt. C in saline was implanted to bridge an 8-mm neural gap in the buccal division of the rabbit facial nerve. At 3 weeks there was a more mature neural organization, greater fascicular organization, and more proliferative neovascularization in NGF-treated regenerates. At 3 and 5 weeks computer-assisted morphometric examination at the midtube revealed no significant difference in the number of myelinated or unmyelinated axons in NGF or Cyt. C treated implants. However, at 5 weeks, NGF regenerates, when compared to their respective preoperative controls, had a greater percentage of myelinated axons (46% vs 18%). For cable graft repair an 8-mm autologous segment of the buccal nerve was removed, rotated 180°, and sutured to bridge the neural gap.

Human facial nerve regeneration was compared in two systems: autologous neural cable grafts (N = 56) and direct end-to-end anastomosis (N = 34). The data were analyzed based on the following criteria: facial symmetry and muscle tone at rest, degree of total facial reinnervation, voluntary motion, synkinesis, and electrophysiologic testing. Facial tone and symmetry at rest, and electrophysiologic tests were similar, while voluntary motion and facial reinnervation were decreased and synkinesis increased in the autologous cable graft repairs. Electrophysiologic tests failed to distinguish between the two repair methods in successful regenerates. Neural cable grafts were associated with more mass movement and less fine precise emotive facial movement. Excellent cable graft repair results diminish with time because of continual progressive synkinesis, which may take up to 4 years to develop. Eight-millimeter neural cable graft repairs of the buccal division of the facial nerve in rabbits (N = 8) demonstrate, at 5 weeks, equal myelinated and more unmyelinated axons than in the normal nerve controls. Neural cable graft repairs demonstrate two features not found in the normal nerve: 1. myelin debris and 2. two subpopulations of axons--extrafascicular and intrafascicular. Myelin debris predisposes towards extrafascicular axon regeneration. Extrafascicular axons are the major neurite regenerates (63%). Intrafascicular axons are the major reinnervators of the distal transected nerve stump. Electrophysiologic studies demonstrate decreased conduction velocities which are related to the number and size of myelinated axonal regenerates. The implications for neurite reinnervation of the autologous cable graft and their role in synkinesis are discussed.

During transhiatal esophagectomy, the esophagus is generally safely and easily dissected posteriorly. However, in 1% to 2% of patients, an aberrant right subclavian artery passes between the esophagus and spine. We demonstrate that transhiatal esophagectomy may be safely performed in these patients when recognition and careful dissection are performed. Thoracic surgeons must be aware of this anomaly in order to prevent laceration of the aberrant right subclavian artery with catastrophic hemorrhage.

Previous reports suggest that exogenous nerve growth factor (NGF) enhanced nerve regeneration in rabbit facial nerves.1 Rabbit facial nerve regeneration in 10-mm Silastic® tubes prefilled with NGF was compared to cytochrome C (Cyt. C), bridging an 8-mm nerve gap. Three weeks following implantation, NGF-treated regenerates exhibited a more mature fascicular organization and more extensive neovascularization than cytochrome-C-treated controls. Morphometric analysis at the midtube of 3- and 5-week regenerates revealed no significant difference in the mean number of myelinated or unmyelinated axons between NGF- and cytochrome-C-treated implants. However, when the number of myelinated fibers in 5-week regenerates were compared to their respective preoperative controls, NGF-treated regenerates had recovered a significantly greater percentage of myelinated axons than cytochrome-C-treated implants (46% vs. 18%, respectively). In addition, NGF-containing chambers reinnervated a higher percentage of myelinated axons in the distal transected neural stumps (49% vs. 34%). Behavioral and electrophysiologic studies demonstrated spontaneous and induced activities in the target muscles when approximately one third of the myelinated axons were recovered in the midchamber (1280 axons). Horseradish peroxidase (HRP) studies demonstrated retrograde axonal transport to the midchamber and proximal transected neural stump. PC12 bioassay demonstrated persistent NGF activity in the intrachamber fluids at 3 (5:1 dilution) and 5 (2:1 dilution) weeks of entubation. Electrophysiologic tests demonstrated a slow conduction velocity of a propagated electrical impulse (43.5 m/s−1vs. 67 m/s−1) and shallow wide compound action potential. In wider defects (15-mm chambers) and longer entubation periods (7 weeks), no regeneration or NGF activity was seen. Therefore, exogenous NGF provides an early but limited neurotrophic effect on the regeneration of the rabbit buccal division of the facial nerve and a limited behavioral and physiological improvement in the target muscles.

The early stages of rabbit peripheral facial nerve regeneration [N = 16], over a 10-mm transectional gap, were analyzed at 1, 3, and 5 weeks of buccal nerve entubation in silicone chambers prefilled with saline. Normal nerve pooled data were obtained in nine nerves. Chronologic morphologic and morphometic light and electron microscopic computer-captured data reveal that the regeneration process can be subdivided into four stages: 1. The establishment of an acellular intergap matrix; 2. the ingrowth of mesodermally derived cells (macrophages, fibroblasts, endothelial cells, etc.) to form an intergap scaffolding; 3. the ingrowth of ectodermally derived cells (neurons, Schwann's cells, etc.) to reconstitute the transected peripheral nerve; and 4. neural maturation by progressive axonal enlargement, myelination, and compartmentalization. The first two stages occur during the first week, the third stage during the third week, and the fourth stage from the fifth week onwards of neural entubation. Morphometic analyses indicate that total neuroregenerates increase in number from 303 +/- 286 to 2693 +/- 1334 (+/- values are standard deviations) and myelination of axons increases from 12% to 48% during the third to fifth week of entubation. The thickness of the myelin (g-ratio) increases from 0.89 +/- .01 to 0.74 +/- .06 (SD) during the same period of time. At the end of the fifth week of entubation, the midchambers contain, on the average, 1279 +/- 980 myelinated axons (30% of normal counts) and 483 (+/- 11.2%) axons cross the chambers to innervate the distal transected neural stump (12.5%). Specific target-organ (quadratus labii superioris muscle) activity can be recaptured with a smaller number (12.5%) of regenerating myelinated axons from the buccal division of the facial nerve during the fifth week of entubation.

Evidence from Bed I, Olduvai, supports the hypothesis that scavenging, not hunting, was the major meat-procurement strategy of hominids between 2 and 1.7 million years ago. Data used to evaluate the hunting and scavenging hypotheses are derived from studying cut marks on Bed I bovids, comparing adaptations necessary for scavenging with those of early hominids, and a pa-leoecological reconstruction of Bed I carcass biotnass, carnivore guild, and hominidforaging area.

Scanning electron microscope (SEM) examination of bone surfaces from the Pleasant Lake mastodon, excavated in southern Michigan, documents features indicative of butchery. These features are identified by comparison with modern bones modified by human and natural processes. We report new studies of (1) marks made by bone tools during removal of meat from and disarticulation of carcasses and (2) use wear developed on bone tools. We also apply previously developed criteria for recognizing stone tool cutmarks and stages in the burning of bone. The Pleasant Lake site, dated to between 10,395 ± 100 and 12,845 ± 165 b.p., provides compelling evidence of mastodon butchery and bone tool use. Another site, near New Hudson, Michigan, provides replication of much of this evidence. Together these sites offer new examples of patterns of bone modification and extend the geographic and temporal representation of the much discussed, but still controversial, late Pleistocene bone technology.

The effects of hyena scavenging on the remains of 75 animals in the Awash National Park, Ethiopia, were examined to provide a modern analogy to the fossil assemblage from Makapan. Brain's recent work ('70, '76) suggests that the actions of carnivores may account for the characteristics of the Makapan assemblage, a theory which contrasts with Dart's ('49, '55, '57, '59) interpretation of the fossils as osteodontokeratic tools and weapons manufactured, collected, and used by australopithecines. The modern assemblage was like that from Makapan in terms of relative representation of skeletal elements and patterns of bone breakage. Observations of hyenas in the Awash also lend support to the hypothesis that the Makapan assemblage may represent the uneaten remains of carnivore kills. The representation of major vertebrate groups at Makapan was compared with their representation at Awash and with their representation in hyena diets in the Serengeti and Ngorongoro Crater (Kruuk, '72). This technique of faunal analysis was unable to detect differences between these groups, despite the fact that the three modern assemblages represent animals that died of different causes. Thus extreme caution must be used in deducing any specific information about the mode of death or taphonomic history of the animals represented in an assemblage on the basis of such faunal analyses.

The efficacy of various therapeutic regimens for the treatment of impetigo was assessed in an experimental animal model. The topical application of gentamicin or bacitracin and removal of scabs were ineffectual. PHisoHex scrubbing delayed healing significantly and resulted in the development of satellite lesions. Healing was significantly promoted by the administration of penicillin, the benzathine variety being more effective than procaine penicillin. Benzathine penicillin was similarly effective in pure streptococcal lesions and in mixed lesions containing penicillin-sensitive or penicillin-resistant staphylococci in addition to streptococci. The development of skin lesions was markedly reduced following prophylactic administration of benzathine penicillin.