Features of cortically evoked swallowing in the awake primate (Macaca fascicularis)

Although the cerebral cortex has been implicated in the control of swallowing, the output organization of the cortical swallowing representation, and features of cortically evoked swallowing, remain unclear. The present study defined the output features of the primate "cortical swallowing representation" with intracortical microstimulation (ICMS) applied within the lateral sensorimotor cortex. In four hemispheres of two awake monkeys, microelectrode penetrations were made at </=1-mm intervals, initially within the face primary motor cortex (face-MI), and subsequently within the cortical regions immediately rostral, lateral, and caudal to MI. Two ICMS pulse trains [35-ms train, 0.2-ms pulses at 333 Hz, </=30 microA (short train stimulus, T/S); 3- to 4-s train, 0.2-ms pulses at 50 Hz, </=60 microA (continuous stimulus, C/S)] were applied at </=500-micron intervals along each microelectrode penetration to a depth of 8-10 mm, and electromyographic (EMG) activity was recorded simultaneously from various orofacial and laryngeal muscles. Evoked orofacial movements, including swallowing, were verified by EMG analysis, and T/S and C/S movement thresholds were determined. Effects of varying ICMS intensity on swallow-related EMG properties were examined by applying suprathreshold C/S at selected intracortical sites. EMG patterns of swallows evoked from various cortical regions were compared with those of natural swallows recorded as the monkeys swallowed liquid and solid material. Results indicated that swallowing was evoked by C/S at approximately 20% of 1,569 intracortical sites where ICMS elicited an orofacial motor response in both hemispheres of the two monkeys, typically at C/S intensities </=30 microA. In contrast, swallowing was not evoked by T/S in either monkey. Swallowing was evoked from four cortical regions: the ICMS-defined face-MI, the face primary somatosensory cortex (face-SI), the region lateral and anterior to face-MI corresponding to the cortical masticatory area (CMA), and an area >5 mm deep to the cortical surface corresponding to both the white matter underlying the CMA and the frontal operculum; EMG patterns of swallows elicited from these four cortical regions showed some statistically significant differences. Whereas swallowing ONLY was evoked at some sites, particularly within the deep cortical area, swallowing was more frequently evoked together with other orofacial responses including rhythmic jaw movements. Increasing ICMS intensity increased the magnitude, and decreased the latency, of the swallow-related EMG burst in the genioglossus muscle at some sites. These findings suggest that a number of distinct cortical foci may participate in the initiation and modulation of the swallowing synergy as well as in integrating the swallow within the masticatory sequence.

Effects of functional disruption of lateral pericentral cerebral cortex on primate swallowing

Bilateral cold block of the intracortical microstimulation (ICMS)-defined swallow cortex markedly affected the ability of monkeys to carry out swallowing. Significant changes also occurred in swallow-related electromyographic (EMG) activity patterns. These findings provide further evidence that the lateral pericentral cortex plays a critical role in the initiation and regulation of swallowing in the primate.

A review of a prison cervical cancer screening program in British Columbia

OBJECTIVE

To review a 1995 Pap smear screening program at Burnaby Correctional Centre for Women (BCCW).

METHOD

129 inmates (15%), were screened in BCCW in 1995. General population data were obtained from the British Columbia Cervical Cytology Screening Program (BC CCSP) Registry.

RESULTS

BCCW inmates aged 25-29 years were 11 times more likely to have high grade cytologic abnormalities on Pap smear screening compared with age-matched general population (p < 10(-10). In the 20-34 year age group, 47% of BCCW inmates had received at least one Pap smear in 1992-1994, compared with 87% of the general population (p < 0.001). There was no relationship between Pap smear results and BCCW inmate ethnicity (p = 0.85).

CONCLUSIONS

Prison inmates presented with more severe abnormalities on Pap smear screening at a younger age, and had received Pap smear screening less frequently, compared with the general population.

Docosahexaenoic acid decreases phospholipase A2 activity in the neurites/nerve growth cones of PC12 cells

Docosahexaenoic acid (DHA) accumulates in nerve growth cones (NGC) during perinatal development and it is neuroprotective in ischemia. Because the phospholipases A2 (PLA2) are present in NGC and these enzymes function in both ischemia and long-term potentiation, the relationship between DHA and PLA2 was investigated in the NGC of nerve growth factor-differentiated PC12 cells. When PC12 cells were incubated with [3H]DHA, it primarily esterified in ethanolamine glycerolipids and concentrated initially in cell bodies with similar levels present in the neurite/nerve growth cone (N/NGC) fraction after 4 days. PLA2 activity in the N/NGC fraction was investigated using [14C]arachidonic acid-labeled phosphatidylinositol ([14C-AA]PI) as substrate. Heat denaturation and pharmacological inhibition showed that much of the PLA2 activity was calcium-independent and secretory rather than cytosolic. Supplementing the media with as little as 33 nM DHA significantly reduced PLA2 activity in the N/NGC fraction.

Plate osteosynthesis of the distal femur: surgical techniques and results

Over the past three decades, the techniques for internal fixation of the distal femur have evolved to provide reliably successful results. The improved outcomes of plate osteosynthesis of distal femur fractures are because of better implants, techniques of anatomic reduction and soft tissue handling, and post-fixation stability with early motion. We review the traditional Arbeitsgemeinschaft für Osteosynthesefragen (AO) surgical techniques for plate osteosynthesis of the distal femur and the results reported using these methods.

Recommendations for recording and calculating the incidence of selected clinical diseases of dairy cattle

The report upon which the current discussion is based was prepared in response to the increasing interest of the dairy industry in the recording of clinical disease data. The major objective was to introduce guidelines and standards for the recording and presentation of the diseases of dairy cattle. Eight clinically identifiable diseases of economic importance to the dairy industry were considered: milk fever, retained placenta, metritis, ketosis, left displaced abomasum, cystic ovarian disease, lameness, and clinical mastitis. Standardized definitions for these diseases were established through consultation with industry partners. Two approaches to summarization and reporting were proposed. For retrospective analysis, which is used when historical data are summarized for genetic evaluation for example, lactational incidence risk (cumulative incidence) has been recommended. For current analysis, which is used for herd health monitoring, a true incidence rate has been recommended. Milk fever and retained placenta were exceptions to the latter because of their short periods of risk. For these two diseases, lactational incidence risks are reported.

The association between cryptococcal variety and immunocompetent and immunocompromised hosts

The varieties of Cryptococcus neoformans serotypes are neoformans and gattii. Data suggest an association between cryptococcal variety and host immune status. In addition, the two varieties differ in their epidemiology and pathogenicity. Furthermore, symptoms, outcome, and response of cryptococcosis to antifungal therapy may vary. The two varieties also differ in immune-modulating effects. Sparse clinical data suggest var. gattii is more virulent and may be more recalcitrant to antifungal therapy. Also, its infections produce more sequelae. A better understanding of how cryptococcal variety influences the clinical course and response to the treatment of cryptococcosis is needed. Clinicians should be aware of the association, especially in patients with refractory disease. It may be useful to type the isolate to the variety level and administer prolonged antifungal therapy.

Association of occlusal, periodontal, and dietary factors with the presence of non-carious cervical dental lesions

PURPOSE

To investigate in vivo the relationship of occlusal stress factors, periodontal health status, and acidic dietary patterns to the presence of non-carious cervical lesions (NCCL) in a convenience sample of undergraduate clinic, adult dental patients.

MATERIALS AND METHODS

Forty three subjects who met the entry criteria were admitted into the study; 178 teeth exhibiting NCCL were evaluated. A dietary assessment focusing on acidic food/beverage intake was used to evaluate nutritional intake over the most recent 24-hour period. Periodontal evaluation included intraoral measurement of gingival attachment loss, assessment of tooth mobility, and radiographic interpretation of percent bone loss using the Schei ruler method. Among the occlusal factors evaluated were shape and orientation of NCCL, presence and location of wear facets, and symptoms and characteristics of centric and eccentric occlusal function.

RESULTS

95% of teeth examined exhibited functional wear facets, indicating a systematic relationship with presence of NCCL (Chi Square = 16.9, P < 0.0001); 48% displayed buccal or incisal facets; 64% were accompanied by balancing interferences in lateral excursion; 98.3% had mobility scores < or = 1; there was no significant association between mobility and facets present (Chi Square = 3.04, P = 0.21); and, no relationship with dietary patterns was found. Group function, that may evolve with age, and/or traumatic occlusion factors may be related to etiology of NCCL. Longitudinal controlled clinical trials are needed to confirm suspected etiologies and establish treatment guidelines for non-carious cervical lesions.

Child abuse and neglect: assessment of dental students' attitudes and knowledge

Although many North American dental schools have increased their curriculum hours dedicated to the issue of child maltreatment, the majority of schools still allocate only one to two clock hours for this subject. The purpose of this study was to evaluate the self-perceived knowledge of and attitude toward child abuse and neglect, of undergraduate dental students at the University of Texas Dental Branch at Houston, as well as the effectiveness of the various educational methods used in the instruction of this material. Students in general, recognized a need for improvement of both the quality and quantity of this aspect of their undergraduate curriculum. The results indicate, however, that the child maltreatment curriculum at this institution had minimal effect on the acquisition and retention of information related to this subject. Dental educators have the responsibility to see that their students are competent, not only in the technical aspects of dentistry, but in their social responsibilities, as well. The ability to recognize suspected cases of child maltreatment is such a responsibility.

Functional properties of neurons in the primate tongue primary motor cortex during swallowing

Recent studies conducted in our laboratory have suggested that the tongue primary motor cortex (i.e., tongue-MI) plays a critical role in the control of voluntary tongue movements in the primate. However, the possible involvement of tongue-MI in semiautomatic tongue movements, such as those in swallowing, remains unknown. Therefore the present study was undertaken in attempts to address whether tongue-MI plays a role in the semiautomatic tongue movements produced during swallowing. Extracellular single neuron recordings were obtained from tongue-MI, defined by intracortical microstimulation (ICMS), in two awake monkeys as they performed three types of swallowing (swallowing of a juice reward after successful tongue task performance, nontask-related swallowing of a liquid bolus, and nontask-related swallowing of a solid bolus) as well as a trained tongue-protrusion task. Electromyographic activity was recorded simultaneously from various orofacial and laryngeal muscles. In addition, the afferent input to each tongue-MI neuron and ICMS-evoked motor output characteristics at each neuronal recording site were determined. Neurons were considered to show swallow and/or tongue-protrusion task-related activity if a statistically significant difference in firing rate was seen in association with these behaviors compared with that observed during a control pretrial period. Of a total of 80 neurons recorded along 40 microelectrode penetrations in the ICMS-defined tongue-MI, 69% showed significant alterations of activity in relation to the swallowing of a juice reward, whereas 66% exhibited significant modulations of firing in association with performance of the trained tongue-protrusion task. Moreover, 48% showed significant alterations of firing in relation to both swallowing and the tongue-protrusion task. These findings suggest that the region of cortex involved in swallowing includes MI and that tongue-MI may play a role in the regulation of semiautomatic tongue movement, in addition to trained motor behavior. Swallow-related tongue-MI neurons exhibited a variety of swallow-related activity patterns and were distributed throughout the ICMS-defined tongue-MI at sites where ICMS evoked a variety of types of tongue movements. These findings are consistent with the view that multiple efferent zones for the production of tongue movements are activated in swallowing. Many swallow-related tongue-MI neurons had an orofacial mechanoreceptive field, particularly on the tongue dorsum, supporting the view that afferent inputs may be involved in the regulation of the swallowing synergy.

Managed care guidelines for the economic evaluation of pharmaceuticals

Foundation Health Corporation, through its National Pharmacy and Therapeutics Committee, requires all pharmaceutical manufacturers and others who wish products to be considered for formulary listing to meet evidentiary and analytical standards in their submission documentation. This article details the evidentiary and analytical standards required from those making submissions and describes the methodological basis of the guidelines. This is the first time, as far as the authors are aware, that a managed care health system in the United States has required formulary submissions not only to meet clinical and economic evaluation standards, but also to take explicit account of the perspective of the managed care group in applying these techniques. Submissions are required to take what is described as a systems impact perspective. This approach is quite different, in both evidentiary and analytical terms, from standards required by health systems in other countries and standards for the economic evaluation of pharmaceuticals proposed by expert groups in the United States.

Dysphagia following anterior cervical spine surgery

Although previous reports have identified dysphagia as a potential complication of anterior cervical spine surgery (ACSS), current understanding of the nature and etiologies of ACSS-related dysphagia remains limited. The present study was undertaken to describe the patterns of dysphagia that may occur following ACSS. Thirteen patients who exhibited new-onset dysphagia following ACSS were studied retrospectively by means of chart review and videofluoroscopic swallow study analysis. Results indicated that a variety of swallowing impairments occurred following ACSS. In 2 patients, prevertebral soft tissue swelling near the surgical site, deficient posterior pharyngeal wall movement, and impaired upper esophageal sphincter opening were the most salient videofluoroscopic findings. In another 5 patients, the pharyngeal phase of swallowing was absent or very weak, with resulting aspiration in 3 cases. In contrast, an additional 4 patients exhibited deficits primarily of the oral preparatory and oral stages of swallowing including deficient bolus formation and reduced tongue propulsive action. Finally, 2 patients exhibited impaired oral preparatory and oral phases, a weak pharyngeal swallow, as well as prevertebral swelling. Thus, a variety of swallowing deficits, due possibly to neurological and/or soft tissue injuries, may occur following ACSS.

Multiple chemical sensitivities, including iatrogenic allergic contact dermatitis, in a patient with chronic actinic dermatitis: implications for management

BACKGROUND

Chronic actinic dermatitis represents a spectrum of photosensitive dermatoses. Phototesting and photopatch testing are necessary to elucidate the specific subtype. Such patients may have multiple cutaneous allergies and photoallergies.

OBJECTIVE

This is a case report of a patient with chronic actinic dermatitis whose condition was worsened by certain sunscreens and corticosteroids. Our purpose was to identify the specific subtype of chronic actinic dermatitis and cutaneous allergens.

METHODS

Phototesting to UVB and UVA was performed. Photopatch testings to standard photoallergens and to Photoplex sunscreen ingredients was performed. Patch testing to standard allergens and proprietary corticosteroids was performed.

RESULTS

Positive photoallergies to Photoplex sunscreen and the UVA screen within Photoplex, Parsol 1789 (4-tert-butyl-4'-methoxydibenzoyl-methane), were identified. Positive allergies to Aclovate (alclometasone dipropionate) cream and ointment and Locoid (hydrocortisone butyrate) ointment were identified. The patient showed increased UVB sensitivity.

CONCLUSION

This is a case report of a patient with chronic actinic dermatitis. A relevant photoallergy to Parsol 1789 and corticosteroid sensitivities to aclometasone and hydrocortisone butyrate were identified. Multiple cutaneous allergens may be identified in patients with chronic actinic dermatoses, and avoidance of known allergens may result in significant improvement of the chronic dermatitis.

Initial assessment and management of common fractures

The initial assessment and management of all fractures follows a standard protocol. All fractured extremities require a thorough neurovascular examination and evaluation of the skin. Fractures are evaluated and described using standard terminology. These important descriptors include open versus closed fractures, the anatomic location of the fracture, the degree and type of displacement, and the fracture pattern. This forces one to become familiar with the personality of the fracture and ultimately facilitates patient care.

Altered expression and changing distribution of the nerve growth associated protein GAP-43 during ocular HSV-1 infection in the rabbit

This research examines changes that occur in neurons during corneal herpes simplex virus (HSV-1) infection and focuses on the nerve growth associated protein GAP-43. Cornea and trigeminal ganglion (TG) of New Zealand white rabbits were examined after inoculation of the McKrae and 17 Syn+ strains of HSV-1 to the cornea. Rabbit tissues were taken during acute, latent and induced reactivation stages of infection. Systemic immunosuppression (intravenous injections of cyclophosphamide and dexamethasone) was used to induce reactivation. Western blotting, immunoblotting and autoradiography with the same antibody were used respectively to verify antibody specificity, measure changes in GAP-43 concentration and localize GAP-43 to neurons in the TG. During acute infection, corneal GAP-43 increased significantly while no change was seen in the TG. GAP-43 content was elevated in TG and cornea during viral latency (post-inoculation days 84-154) for both HSV-1 strains. When latent virus was reactivated, the corneal concentration of GAP-43 was more than double that of normal rabbits and the concentration of GAP-43 in TG was reduced compared to the non-reactivated, latently-infected TG. In summary, HSV-1 infected TG neurons expressed more GAP-43 than control neurons and immunosuppressive therapy led not only to viral reactivation and increased GAP-43 concentrations in cornea but also to decreased GAP-43 concentrations in TG. These results suggest that factors which maintain HSV-1 latency and induce reactivation could be linked to elements regulating GAP-43 expression.

Light adaptation of cyclic electron transport through Photosystem I in the cyanobacterium Synechococcus sp. PCC 7942

Photosystem I-driven cyclic electron transport was measured in intact cells of Synechococcus sp PCC 7942 grown under different light intensities using photoacoustic and spectroscopic methods. The light-saturated capacity for PS I cyclic electron transport increased relative to chlorophyll concentration, PS I concentration, and linear electron transport capacity as growth light intensity was raised. In cells grown under moderate to high light intensity, PS I cyclic electron transport was nearly insensitive to methyl viologen, indicating that the cyclic electron supply to PS I derived almost exclusively from a thylakoid dehydrogenase. In cells grown under low light intensity, PS I cyclic electron transport was partially inhibited by methyl viologen, indicating that part of the cyclic electron supply to PS I derived directly from ferredoxin. It is proposed that the increased PSI cyclic electron transport observed in cells grown under high light intensity is a response to chronic photoinhibition.

Preparing for the "silver age of dentistry"

Providing oral health care to older adults will be a challenging and rewarding part of dental practice in the years ahead. It will include understanding normal aging, appreciation of the pathophysiology of chronic diseases experienced by many elderly, and application of key principles of pharmacology in care of patients receiving medications for treatment of these diseases. It will involve an understanding of the interaction of systemic conditions with oral health status, adequate diagnosis of oral disease, and appropriate rational treatment planning with a strong emphasis on preventive dentistry. It will include care provided in nursing homes or during housecalls for the homebound. Dentist-geriatricians will be working with teams of healthcare professionals that include physicians, dentists, podiatrists, ophthalmologists, nurses, social workers, nutritionists, pharmacists, and occupational and physical therapists. Above all, the team will provide skilled compassionate care, which is always good business!

Management of dry mouth in elderly patients

Xerostomia is not a natural consequence of the aging process. Although dry mouth is not often found to be a chief complaint of elderly patients, it is a common problem that usually receives inadequate attention. Xerostomia is the feeling of dry mouth due to insufficient secretion of saliva. It is most common among the elderly as a result of adverse effects of drug therapy, head and neck radiation, or autoimmune diseases. Chronic xerostomia has a debilitating effect on the integrity of the hard and soft tissues of the mouth. It often causes difficulty in speaking, tasting, eating, swallowing and denture retention. The goals of treatment are to stimulate salivary flow, or to restore oral moistness and prevent or alleviate the uncomfortable, harmful sequelae of xerostomia. Dentists can significantly enhance the quality of life for xerostomia sufferers by effectively managing the xerostomia sequelae in a compassionate, understanding manner.

Retiring some myths about aging and oral health

Research on the oral health status of elderly populations has been limited in frequency and scope. There is a lack of good descriptive and longitudinal data on salivary gland function, oral mucosal status, and oral sensory performance in health and disease across the adult life span. Thus, confusion for practitioners and patients alike arises from unsubstantiated stereotypes about aging and oral health. There are some commonalities in the origins of the myths discussed in this article. First, many aging generalizations were based on studies that did not account for the health and medication status of the subjects. Second, most aging studies are cross-sectional designs which can result in misleading conclusions due to the age cohort effect. Third, many studies on the histology of aging oral tissues were laboratory animal studies, with results that cannot be generalized to human populations. Fourth, findings on oral health changes are often confounded or influenced by differences in functional status (e.g., the ability to care for oneself), nutritional health, health beliefs and expectations within the study subjects. Fifth, other changes due to aging may have an indirect effect on oral health, for example, an age-related decline in immune function. Sixth, the "older-old" group of elderly commonly labor under misconceptions of normal aging changes. Historically they have not sought dental care as often as the younger elders. This health care seeking behavior is expected to change dramatically when the baby boom generation joins the elderly ranks. The goals of oral health care for the elderly are consistent with those of other health care providers involved in geriatric care, namely maximizing functional performance, fostering independence, and enhancing their quality of life. Dental professionals would be well advised to apply a healthy dose of skepticism to any generalizations about debilitating changes in oral health due to aging alone. Most changes in oral health experienced by the elderly are not the result of age itself, but are the consequences of systemic disease, pharmacotherapy, functional disabilities, and cognitive impairment. When unexplained deleterious changes are seen in the oral health of elderly patients, the knowledgeable and reflective practitioner will account for local, systemic, and environmental factors in formulating a plan of care. In the opening paragraph, questions were posed about the mucosal integrity of a "little old lady." The most beneficial approach for her and all our older patients is to plan treatment utilizing current knowledge about aging and avoiding the traps created by myths and stereotypes. It is time to retire these myths before the baby boomers join the ranks of the retired.

Hyperosmolar nonketotic diabetic syndrome following treatment of human immunodeficiency virus infection with didanosine

OBJECTIVE

To determine whether didanosine (DDI), one of the drugs commonly used to treat infection with human immunodeficiency virus (HIV), contributes to the development of diabetes and hyperosmolar nonketotic diabetic syndrome (HNKDS).

CASE SUMMARY

One female patient was treated with DDI for infection with HIV during pregnancy. Soon after starting DDI treatment, she developed diabetes, which progressed to HNKDS.

CONCLUSIONS

Although not reported in the literature, hyperglycemia following treatment with DDI has been noted in 82 patients and is usually associated with pancreatitis. DDI should be recognized as one of the drugs known to potentially cause diabetes and HNKDS. With the increasing use of DDI and other drugs that cause hyperglycemia, such as pentamidine and dapsone, blood glucose should be monitored frequently in the HIV-infected patients.