The impact of real-world cardiovascular-related pharmacogenetic testing in an insured population.

BACKGROUND: Pharmacogenomics is intended to help clinicians provide the right drug to the right patient at an appropriate dose. However, limited evidence of clinical utility has slowed uptake of pharmacogenomic testing (PGT). OBJECTIVE: To evaluate the impact of real-world cardiovascular (CV)-related PGT on clinical outcomes, healthcare resource utilisation (HCRU) and cost in a large, heterogeneous population. METHODS: Individuals with Medicare Advantage Prescription Drug, Medicaid, or commercial coverage between 1/1/2011 and 9/30/2015 and ≥1 atherosclerotic CV-related diagnosis were identified. Those with ≥1 claim for CV-related PGT were included in the test group (index date = 1st PGT claim) and matched 1:2 to controls without PGT. Individuals aged <22 or ≥90 years old on the index date, with <12 months continuous enrollment before and after the index date, or without an ASCVD-related diagnosis in the 12-month pre-index period were excluded. The primary outcome was occurrence of a major CV event during the 12-month post-index period. RESULTS: After adjustment, the PGT group was significantly more likely to experience ischaemic stroke, pulmonary embolism, deep vein thrombosis or a composite event compared with controls. Adjusting for baseline characteristics, HCRU was significantly higher for the test group across all measured outcomes except all-cause and ASCVD-related inpatient admissions. Median all-cause and ASCVD-related healthcare costs were significantly higher for the test group. CONCLUSIONS: Real world PGT in a large population did not improve outcomes. Tailoring medication therapy to each patient holds great promise for providing quality care but a deeper understanding of how widespread utilisation of PGT might impact objective health outcomes is needed.

Temporal patterns of digestive enzyme activities and feeding rate in gammarids (Gammarus fossarum) exposed to inland polluted waters.

The aim of this study was to use digestive enzyme activities in Gammarus fossarum as biomarkers during active biomonitoring. Standardised gammarids were transplanted for 7 days to five sites in the Riou Mort watershed contaminated by polymetallic pollution. This experiment was conducted on seven different dates from February 2009 to June 2010. Feeding rates were tracked, along with amylase, cellulase and trypsin activities. We found that feeding rate and digestive capacity were reduced in the most polluted site, "Joany," in comparison with the reference site "Up.Lot". The results suggested that trypsin was more sensitive than the other two carbohydrases. In the four other sites, seasonal differences were observed during the 2yr but no clear pattern can be established. This study highlights the ability of G. fossarum to demonstrate environmental disturbances and suggests the use of a caging process in certain seasons. Caging organisms and feeding ad libitum is advantageous, as it reduces inter-individual variability and removes dependence on the native food fluctuations. However, confounding factors other than temperature were present, and the interpretation of digestive enzyme activities is complex.

Association of Health-Related Social Needs With Quality and Utilization Outcomes in a Medicare Advantage Population With Diabetes.

Importance: Recent research highlights the association of social determinants of health with health outcomes of patients with type 2 diabetes (T2D). Objective: To examine associations between health-related social needs (HRSNs) and health care quality and utilization outcomes in a Medicare Advantage population with T2D. Design, Setting, and Participants: This cross-sectional study used medical and pharmacy claims data from 2019. An HRSN survey was given between October 16, 2019, and February 29, 2020, to Medicare Advantage beneficiaries. Inclusion criteria were diagnosis of T2D, age of 20 to 89 years, continuous Medicare Advantage enrollment in 2019, and response to the HRSN survey. Data were analyzed between June 2021 and January 2022. Exposures: Enrollment in Medicare Advantage, diagnosis of T2D, and completion of a survey on HRSNs. Main Outcomes and Measures: Quality outcomes included diabetes medication adherence, statin adherence, completion of a glycated hemoglobin (HbA1c) laboratory test in the past 12 months, and controlled HbA1c. Utilization outcomes included all-cause hospitalization, potentially avoidable hospitalization, emergency department discharge, and readmission. Results: Of the 21 528 Medicare Advantage beneficiaries with T2D included in the study (mean [SD] age, 71.0 [8.3] years; 55.4% women), most (56.9%) had at least 1 HRSN. Among the population with T2D reporting HRSNs, the most prevalent were financial strain (73.6%), food insecurity (47.5%), and poor housing quality (39.1%). In adjusted models, loneliness (odds ratio [OR], 0.85; 95% CI, 0.73-0.99), lack of transportation (OR, 0.80; 95% CI, 0.69-0.92), utility insecurity (OR, 0.86; 95% CI, 0.76-0.98), and housing insecurity (OR, 0.78; 95% CI, 0.67-0.91) were each associated with lower diabetes medication adherence. Loneliness and lack of transportation were associated with increased emergency visits (marginal effects of 173.0 [95% CI, 74.2-271.9] and 244.6 [95% CI, 150.4-338.9] emergency visits per 1000 beneficiaries for loneliness and transportation, respectively). Food insecurity was the HRSN most consistently associated with higher acute care utilization (marginal effects of 84.6 [95% CI, 19.8-149.4] emergency visits, 30.4 [95% CI, 9.5-51.3] inpatient encounters, and 17.1 [95% CI, 4.7-29.5] avoidable hospitalizations per 1000 beneficiaries). Conclusions and Relevance: In this cross-sectional study of Medicare Advantage beneficiaries with T2D, some HRSNs were associated with care quality and utilization. The results of the study may be used to direct interventions to the social needs most associated with T2D health outcomes and inform policy decisions at the insurance plan and community level.

Health-Related Social Needs Among Older Adults Enrolled In Medicare Advantage.

Among older adults enrolled in Medicare Advantage, health-related social needs are highly prevalent, with financial strain, food insecurity, and poor housing quality the most commonly reported. The distribution of health-related social needs is uneven, with significant disparities according to race, socioeconomic status, and sex.

Association Between Self-reported Health-Related Social Needs and Acute Care Utilization Among Older Adults Enrolled in Medicare Advantage.

Importance: There is increased focus on identifying and addressing health-related social needs (HRSNs). Understanding how different HRSNs relate to different health outcomes can inform targeted, evidence-based policies, investments, and innovations to address HRSNs. Objective: To examine the association between self-reported HRSNs and acute care utilization among older adults enrolled in Medicare Advantage. Design Setting and Participants: This cross-sectional study used data from a large, national survey of Medicare Advantage beneficiaries to identify the presence of HRSNs. Survey data were linked to medical claims, and regression models were used to estimate the association between HRSNs and rates of acute care utilization from January 1, 2019, through December 31, 2019. Exposures: Self-reported HRSNs, including food insecurity, financial strain, loneliness, unreliable transportation, utility insecurity, housing insecurity, and poor housing quality. Main Outcomes and Measures: All-cause hospital stays (inpatient admissions and observation stays), avoidable hospital stays, all-cause emergency department (ED) visits, avoidable ED visits, and 30-day readmissions. Results: Among a final study population of 56 155 Medicare Advantage beneficiaries (mean [SD] age, 74.0 [5.8] years; 32 779 [58.4%] women; 44 278 [78.8%] White; and 7634 [13.6%] dual eligible for Medicaid), 27 676 (49.3%) reported 1 or more HRSNs. Health-related social needs were associated with statistically significantly higher rates of all utilization measures, with the largest association observed for avoidable hospital stays (incident rate ratio for any HRSN, 1.53; 95% CI, 1.35-1.74; P < .001). Compared with beneficiaries without HRSNs, beneficiaries with an HRSN had a 53.3% higher rate of avoidable hospitalization (incident rate ratio, 1.53; 95% CI, 1.35-1.74; P < .001). Financial strain and unreliable transportation were each independently associated with increased rates of hospital stays (marginal effects of 26.5 [95% CI, 14.2-38.9] and 51.2 [95% CI, 30.7-71.8] hospital stays per 1000 beneficiaries, respectively). All HRSNs, except for utility insecurity, were independently associated with increased rates of ED visits. Unreliable transportation had the largest association with increased hospital stays and ED visits, with marginal effects of 51.2 (95% CI, 30.7-71.8) and 95.5 (95% CI, 65.3-125.8) ED visits per 1000 beneficiaries, respectively. Only unreliable transportation and financial strain were associated with increased rates of 30-day readmissions, with marginal effects of 3.3% (95% CI, 2.0%-4.0%) and 0.4% (95% CI, 0.2%-0.6%), respectively. Conclusions and Relevance: In this cross-sectional study of older adults enrolled in Medicare Advantage, self-reported HRSNs were common and associated with statistically significantly increased rates of acute care utilization, with variation in which HRSNs were associated with different utilization measures. These findings provide evidence of the unique association between certain HRSNs and different types of acute care utilization, which could help refine the development and targeting of efforts to address HRSNs.

Improving laboratory monitoring at initiation of drug therapy in ambulatory care: a randomized trial.

BACKGROUND: The importance of laboratory monitoring for drugs is reflected in product labeling and published guidelines, but monitoring recommendations are followed inconsistently. Opportunity exists to improve monitoring, with the potential to decrease therapy complications. METHODS: The objective of this randomized trial was to determine whether computerized alerts were effective at increasing the percentage of ambulatory patients with laboratory monitoring at initiation of drug therapy. Physicians and pharmacists teamed up to develop organization-specific guidelines for monitoring selected drugs. In collaboration with physicians, pharmacists were alerted to missing laboratory test results, ordered missing tests, reminded patients to obtain tests, assessed test completion, reviewed test results, and managed abnormal results. Eligible individuals included patients with therapy initiated for any of 15 drugs among 400,000 health plan members. RESULTS: In the intervention group, 79.1% (n = 4076; 95% confidence interval [CI], 78.0%-80.2%) of dispensings were monitored compared with 70.2% (n = 3522; 95% CI, 68.9%-71.5%) in the usual-care group (P < .001). For example, 78.6% of amiodarone (95% CI, 73.1%-83.5%) dispensing was monitored in the intervention group vs 51.4% (95% CI, 44.4%-58.4%) in the group receiving usual care (P < .001). CONCLUSIONS: This study demonstrates the effectiveness of a computerized tool plus collaboration among health care professionals at increasing the percentage of patients receiving laboratory monitoring at initiation of therapy. Coupling data available from information systems with the knowledge and skills of physicians and pharmacists can result in improved patient monitoring.

Laboratory monitoring of drugs at initiation of therapy in ambulatory care.

BACKGROUND AND OBJECTIVES: Product labeling and published guidelines reflect the importance of monitoring laboratory parameters for drugs with a risk of organ system toxicity or electrolyte imbalance. Limited information exists about adherence to laboratory monitoring recommendations. The objective of this study was to describe laboratory monitoring among ambulatory patients dispensed medications for which laboratory testing is recommended at therapy initiation. DESIGN AND SUBJECTS: We conducted a retrospective cross-sectional analysis of patients in 10 geographically distributed health maintenance organizations who were newly prescribed medications with recommended laboratory test monitoring. The main outcome measure was the proportion of initial drug dispensing without recommended baseline laboratory monitoring for 35 newly initiated drugs or drug classes. RESULTS: One hundred seven thousand, seven hundred sixty-three of 279,354 (39%) initial drug dispensings occurred without recommended laboratory monitoring. Patients without monitoring were younger than patients who had monitoring (median 57 vs 61 years, P<.001). Thirty-two percent of dispensings where a serum creatinine was indicated did not have it evaluated (range across drugs, 12% to 61%); 39% did not have liver function testing (range 10% to 75%); 32% did not have hematologic monitoring (range 9% to 51%); and 34% did not have electrolyte monitoring (range 20% to 62%) (P<.001). CONCLUSIONS: Substantial opportunity exists to improve laboratory monitoring of drugs for which such monitoring is recommended. This study emphasizes the need for research to identify the clinical implications of not conducting recommended laboratory monitoring, existing barriers to monitoring, and methods to improve practice.

Patient self-management of continuous subcutaneous insulin infusion.

Continuous subcutaneous insulin infusion (CSII) is one of the ways to control blood glucose for prolonged periods. This study was undertaken to establish the long-term feasibility and efficacy of CSII with patient self-management. Patients were instructed to maintain their calorie and carbohydrate intake. Basal infusion of insulin, representing 50% of the total pre-CSII dose, was supplemented by boluses of insulin based on carbohydrate intake for each meal. With this type of regimen, blood glucose and M-values were easily normalized during the physician-directed periods. This study demonstrated that near-normalization of blood glucose, M-values, and glycosylated hemoglobin was maintained after a 1 1/2-yr period of patient self-management. We attributed this successful management in part to the protocol used, in which boluses were related solely to carbohydrate intake while basal insulin was adjusted according to fasting blood glucose. The chronic normalization of blood glucose resulted in improvement of platelet function as witnessed by responsiveness to antiaggregating (PGE1) and aggregating (epinephrine) agents. An improvement was noticed in doppler measurement of ankle-arm blood pressure and a near-normalization of nerve latency and conductivity was observed.

Clinical and methodological factors related to reliability of the best-estimate diagnostic procedure.

OBJECTIVE: The reliability and accuracy of the best-estimate diagnostic procedure were examined, and factors associated with reliability were determined. METHOD: The subjects were 134 members of large multigenerational pedigrees densely affected by bipolar disorders or schizophrenia. Three best-estimate diagnoses were derived: first, by a research psychiatrist and research assistant unblind to the relatives' diagnoses; second, by two blind independent psychiatrists; third, by a panel of four blind psychiatrists. The subjects were characterized on several clinical and methodological variables, which were used to compare the agreements of two types of best-estimate diagnoses with the disagreements. RESULTS: There was satisfactory agreement between the unblind and blind consensus best-estimate diagnoses and between the two blind independent psychiatrists. Latent class analyses revealed that limited sensitivity was the main source of imperfect reliability. Confusability analyses revealed that the most problematic diagnostic distinctions involved schizoaffective disorder, which was confused with schizophrenia, bipolar I disorder, and schizophreniform disorder. Blindness significantly affected diagnostic outcome in latent class analyses. Moreover, for diagnostic disagreements, unblind diagnoses had greater continuity with the most predominant diagnosis in the pedigree than did blind diagnoses. Diagnostic disagreements were associated with the presence of mixed affective and psychotic symptoms, less diagnostic certainty, and shorter duration of illness. CONCLUSIONS: These results suggest that it is possible to identify cases that are more likely to lead to diagnostic disagreements in family and epidemiological studies and that blind diagnoses may help to prevent false positive diagnoses, which may be particularly detrimental to genetic linkage analyses.

Type I fiber atrophy and internal nuclei. A form of centronuclear myopathy?

A 6-year-old boy had a myopathy characterized by central nuclei with type I muscle fiber atrophy and preponderance. Study of the family members demonstrated no abnormalities with the exception of an unusually high incidence of centrally located muclei in the muscle biopsy specimen of the mother. A review of the literature disclosed a limited number of cases with identical morphological abnormalities, suggesting that they constitute a form of centronuclear myopathy with some distinctive clinical features.

Sensory neuropathy associated with primary biliary cirrhosis. Histologic and morphometric studies.

Sensory symptoms can develop in the course of primary biliary cirrhosis. They have been attributed to xanthomatous infiltrates of the nerves. We report a case of a young woman suffering from pure sensory neuropathy starting at a time when evidence of liver disease was minimal. Histologic and morphometric studies of sural nerve biopsy specimens obtained from calf and ankle showed a dying-back type of axonal degeneration predominantly affecting large myelinated fibers. No lipid-containing cells were seen, which raises the possibility that other mechanisms related to primary biliary cirrhosis are involved in the pathogenesis of the neuropathy.

Polyneuropathy and folate deficiency.

We studied five patients (two men and three women, age between 58 and 76 years) with clinical and electrophysiological signs of polyneuropathy. Routine neurological, hematological, and gastroenterological studies as well as procedures to test fat malabsorption were performed. Folate determinations were done using both radioactive and Lactobacillus casei methods. Two patients displayed the signs of subacute combined degeneration of the spinal cord with polyneuropathy, while three had only signs of neuropathy. All had low serum folate concentration, long-standing gastrointestinal disease, and deficient folate intake. The D-xylose absorption test gave values in all patients, while none displayed the classical malabsorption syndrome. The patients had substantial improvement or recovered (according to clinical and electrophysiological measurements) after periods ranging from 9 to 39 months of folate therapy. Such acquired folate-responsive polyneuropathy has two principal characteristics: mixed sensorimotor with mainly sensory deficits, and involvement of one or both of the lower extremities much more extensively than the upper extremities.

Vasculitic neuropathy in rheumatoid disease and Sjögren syndrome.

Two patients with rheumatoid arthritis and one with Sjögren syndrome had a severe sensorimotor neuropathy preceding or up to 5 years after the onset of the disease. Electrophysiologic and sural nerve biopsy studies revealed an axonal neuropathy. Myelinated fibers were affected to a greater extent than unmyelinated axons. Peripheral nerve damage was related to occlusion of the vasa nervorum, since vasculitic involvement of epineurial vessels was observed in all patients. Despite the severity of the neuropathy, it may recover, because, compared with axons, Schwann cells are perhaps less vulnerable to ischemia.

6p24-22 region and major psychoses in the Eastern Quebec population. Le Groupe IREP.

Recent reports of a linkage trend in 6p24-22 for schizophrenia (SZ), in different samples, were tempered by the concurrent evidence of negative reports in other samples. In the studies showing positive results, different definitions of affection and a wide spectrum of diagnoses were used. Our objectives were not only to test for linkage at 6p24-22 in the Eastern Quebec population, but also to test whether this putative vulnerability locus was either selectively linked to schizophrenia (SZ), or to bipolar disorder (BP), or to both major psychoses. Parametric and nonparametric linkage analyses with 12 microsatellite markers in 6p24-p22 were performed on a sample of 18 large multigenerational pedigrees (N = 354) either affected by SZ, or by BP, or equally affected by both major psychoses (i.e., mixed pedigrees). Three affection definitions were usually tested in our program: one on schizophrenia (SZ), one on bipolar disorder (BP), and one that comprised SZ and BP under the hypothesis of a susceptibility locus common to both in major psychoses (common locus, CL). The results of parametric analyses did not support a major gene hypothesis. However, in one large mixed pedigree (#151), we observed with the common locus phenotype (CL) lod scores of 2.49 and 2.15, respectively, at the D6S296 and D6S277 loci under a dominant model. Our data suggest the presence of a potential vulnerability locus at 6p24-22 that could be related to both schizophrenia and bipolar affective disorder. These results may be seen as congruent with former studies that used schizoaffective as well as schizophrenia diagnoses as entry criteria for the affected families, and used an affection definition that comprised affective psychoses as well as schizophrenia.

Decreased horseradish peroxidase labeling in deafferented spinal motoneurons of the rat.

It has been suggested that the incorporation and retrograde transport of horseradish peroxidase (HRP) were linked to the level of neuronal activity. Therefore one could postulate that the motor impairment resulting from dorsal rhizotomy affects the HRP labeling of spinal motoneurons in the absence of morphological damage to the motor system. This hypothesis was tested in the adult rat by sectioning bilaterally the L3-L5 dorsal roots. 2-18 months after surgery, the L4 radicular nerve was immersed in a solution of HRP. Labeled motoneurons were counted together with the motor axons of the L4 ventral root and results were compared with values obtained in paired controls. Deafferentation resulted in a crippling deficit of lower limb movements with disuse atrophy of muscle fibers but had no effect on the fiber population of the sciatic nerve and the L4 ventral root. Whereas in normal animals the L4 HRP-labeled motoneurons represented 71.9-98.3% (average 85.4) of the motor axonal counts, in animals studied 4, 12 and 18 months after dorsal rhizotomy, the number of motoneurons containing HRP granules constituted only 20.1-55.7% (average 46.2) of the number of motor axons and many of the labeled cells were faintly stained. These findings, which may reflect either a decreased retrograde transport of HRP in deafferented motoneurons or an increased turnover of the enzyme in the cell body, call attention to the possibility that the degree of activity in neuronal pathways influences HRP labeling.

Differences in horseradish peroxidase labeling of sensory, motor and sympathetic neurons following chronic axotomy of the rat sural nerve.

In an attempt to clarify the ultimate fate of permanently axotomized adult primary neurons, horseradish peroxidase (HRP) was used as a cell marker to label the motor, sensory and postganglionic sympathetic neurons of rat sural nerves which had been sectioned at the ankle and prevented from regenerating for periods of up to 80 weeks. Axotomy did not affect sympathetic neurons, but resulted 4 weeks later in a sudden reduction in the number of labeled sensory and motor cells which persisted to the end of the study. The missing neuronal population amounted to 44.4% and 45.9% respectively of the normal sensory and motor contingent and included most of the large afferent and efferent neurons. However, examination of sural nerves at the thigh, 30 mm proximal to the neuroma, revealed marked axonal atrophy but no change in the number of myelinated and unmyelinated fibers up to 52 weeks after axotomy. Such prolonged survival of the peripheral processes is indirect evidence that axotomized neurons can endure long-term detachment from their end organs and suggests that the lack of HRP labeling in certain sensory and motor neurons does not imply their degeneration, but expresses one of many retrograde dysfunctions triggered by axotomy.

Motor, sympathetic and sensory innervation of rat skeletal muscles.

This study reports on the location, number and size of motor, sympathetic and sensory neurons innervating the following muscles of rat: quadriceps femoris (QF), tibialis anterior (TA), extensor digitorum longus (EDL), peroneus longus (PL), gastrocnemius medius (GM) and soleus (SOL). Cells were labelled by application of horseradish peroxidase (HRP) to transected muscle nerves. Counts of neurons were compared with counts of myelinated (MF) and unmyelinated (UMF) fibers in normal, deafferented and chemically sympathectomized nerves. The topographical arrangement of spinal motor nuclei resembled that reported previously in other mammals and birds. Sensory somata were aggregated without precise somatotopic organization, preferentially in one of the lumbar dorsal root ganglia at a segmental level corresponding to that of the motor innervation. Because lumbar sympathetic ganglia were often poorly circumscribed, the segmental position of sympathetic ganglion cells could not be localized with certainty. Sensory and sympathetic somata demonstrated a unimodal size-frequency distribution, while QF, TA and PL motoneurons could be subdivided according to size in alpha and gamma cells. For all muscles except unsuccessfully deafferented QF, counts of motor fibers after deafferentation correlated closely with counts of labelled motoneurons. Similarly, estimates of sympathetic axons, averaging 30,7% of the UMF, in most instances exceeded only marginally the ganglion cell population. In contrast, the number of peripheral afferent fibers outnumbered markedly that of sensory cell bodies, with an average of 2.8 axons per ganglion cell.

Multipotentiality of Schwann cells in cross-anastomosed and grafted myelinated and unmyelinated nerves: quantitative microscopy and radioautography.

Cross-anastomoses and autogenous grafts of unmyelinated and myelinated nerves were examined by electron microscopy and radioautography to determine if Schwann cells are multipotential with regard to their capacity to produce myelin or to assume the configuration seen in unmyelinated fibres. Two groups of adult white mice were studied. (A) In one group, the myelinated phrenic nerve and the unmyelinated cervical sympathetic trunk (CST) were cross-anastomosed in the neck. From 2 to 6 months after anastomosis, previously unmyelinated distal stumps contained many myelinated fibres while phrenic nerves joined to proximal CSTs became largely unmyelinated. Radioautography of distal stumps indicated that proliferation of Schwann cells occurred mainly in the first few days after anastomosis but was also present to a similar extent in isolated stumps. (B) In other mice, CSTs were grafted to the myelinated sural nerves in the leg. One month later, the unmyelinated CSTs became myelinated and there was no radioautographic indication of Schwann cell migration from the sural nerve stump to the CST grafts. Thus, Schwann cell proliferation in distal stumps is an early local response independent of axonal influence. At later stages, axons from the proximal stumps cause indigenous Schwann cells in distal stumps from the previously unmyelinated nerves to produce myelin while Schwann cells from the previously unmyelinated nerves to produce myelin while Schwann cells from the previously myelinated nerves become associated with unmyelinated fibres. Consequently, the regenerated distal nerve resembled the proximal stump. It is suggested that this change is possible because Schwann cells which divide after nerve injury reacquire the developmental multipotentiality which permits them to respond to aoxonal influences.

A comparative study of the effects of chronic axotomy, crush lesion and re-anastomosis of the rat sural nerve on horseradish peroxidase labelling of primary sensory neurons.

Chronic axotomy is detrimental to the incorporation of horseradish peroxidase (HRP) by neurons of the central and peripheral nervous system. Using the rat sural nerve as a model, this study aimed to determine the effects of other types of nerve injury on the peroxidase labelling of dorsal root ganglion (DRG) cells. Compared to the decreased labelling occurring shortly after permanent transection of the sural axons at the ankle, crush injury of the nerve had no effect on the number and size distribution of peroxidase-stained cells. Re-anastomosing the sural nerve to its own distal segment or to the tibial nerve delayed the changes in HRP neuronal labelling, which subsequently were less severe in neurons allowed to reinnervate their own nerve. It also sustained the incorporation of HRP by many large DRG neurons, a function which is lost shortly after these cells are chronically axotomized. Nerve re-anastomosis also prevented the retrograde atrophy of myelinated and unmyelinated nerve fibers which is triggered by permanent transection. Based on the preservation of fiber counts in the sural nerves proximal to the site of surgery, with no evidence of degeneration, our observations possibly reflect alterations in the peroxidase metabolism of DRG neurons depending on the type of axonal injury they sustained and the possibility they had upon regeneration to contact endoneurial tubes and ultimately their original end-organs.