Production of 5–15 µm Diameter Alginate-Polylysine Microcapsules by an Air-Atomization Technique

A novel method of preparing small-sized microcapsules using a Turbotak air-atomizer is reported. Alginate-polylysine microcapsules containing Bacillus Calmette Guérin vaccine have been prepared by an adaptation of the method of Lim (1) which allows the manufacture of small-sized microcapsules. A Turbotak is used to spray sodium alginate solution into calcium chloride solution to form temporary calcium alginate microgel capsules. These temporary microgel droplets are subsequently cross-linked with polylysine to form permanent membranes. Microcapules in the size range of 5–15 µm have been produced which can be compared to an average diameter of 300 µm obtained by the method reported by Lim. The microcapsule size is dependent on the conditions of operation of the Turbotak and the concentration of the sodium alginate solution. Particles within the size range 5–15 µm can be reproducibly manufactured using the conditions of operation reported here. Other size ranges below the minimum of 300 µm reported by Lim are also feasible using this technique.     

A rejoinder to Professor Bruening

Point and Counterpoint

A rejoinder to Professor Bruening     

Recoding, storage, rehearsal and grouping in verbal short-term memory: an fMRI study

Functional magnetic resonance imaging (fMRI) of healthy volunteers is used to localise the processes involved in verbal short-term memory (VSTM) for sequences of visual stimuli. Specifically, the brain areas underlying (i) recoding, (ii) storage, (iii) rehearsal and (iv) temporal grouping are investigated. Successive subtraction of images obtained from five tasks revealed a network of left-lateralised areas, including posterior temporal regions, supramarginal gyri, Broca's area and dorsolateral premotor cortex. The results are discussed in relation to neuropsychological distinctions between recoding and rehearsal, previous neuroimaging studies of storage and rehearsal, and, in particular, a recent connectionist model of VSTM that makes explicit assumptions about the temporal organisation of rehearsal. The functional modules of this model are tentatively mapped onto the brain in light of the imaging results. Our findings are consistent with the representation of verbal item information in left posterior temporal areas and short-term storage of phonological information in left supramarginal gyrus. They also suggest that left dorsolateral premotor cortex is involved in the maintenance of temporal order, possibly as the location of a timing signal used in the rhythmic organisation of rehearsal, whereas Broca's area supports the articulatory processes required for phonological recoding of visual stimuli.     

Modeling place fields in terms of the cortical inputs to the hippocampus

A model of place-cell firing is presented that makes quantitative predictions about specific place cells' spatial receptive fields following changes to the rat's environment. A place cell's firing rate is modeled as a function of the rat's location by the thresholded sum of the firing rates of a number of putative cortical inputs. These inputs are tuned to respond whenever an environmental boundary is at a particular distance and allocentric direction from the rat. The initial behavior of a place cell in any environment is simply determined by its set of inputs and its threshold; learning is not necessary. The model is shown to produce a good fit to the firing of individual place cells, and populations of place cells across environments of differing shape. The cells' behavior can be predicted for novel environments of arbitrary size and shape, or for manipulations such as introducing a barrier. The model can be extended to make behavioral predictions regarding spatial memory.     

A new cranial access device for cerebral monitoring

We report the design and clinical application of a new cranial access device (triple bolt) designed to transmit intracranial pressure monitors, multiparameter sensors, microdialysis catheters and laser doppler probes into the cerebral parenchyma. The objective was to achieve insertion on the Neuro-Critical Care Unit, imaging compatibility, angled trajectories and versatility of monitor application. The bolt has been successfully applied to 100 patients with severe head injury and subarachnoid haemorrhage.     

STRESS FRACTURES: EFFECT OF PRIOR PHYSICAL ACTIVITY,SPORTS PARTICIPATION AND MILITARY TRAINING

A study was carried out to find out the effects of prior physical activity, sports participation and prior military training on the incidence of stress fractures among Gentlemen Cadets (GC''s) undergoing military training at Indian Military Academy (IMA). One thousand and fourteen GC''s were followed up for a period of 12 weeks. Thirty-seven GC''s developed stress fractures during the study period. The incidence of stress fractures was significantly higher in GC''s without any prior military training (p=0.0009). They were compared with 100 healthy controls drawn from the study population to study the influence of the other mentioned factors. There was no significant association between prior physical activity and stress fractures (OR=0.74, 95% CL=0.26 to 2.05, p=0.688). There was also no significant relationship between sports participation and stress fractures (OR=0.79. 95% CCL=0.35 to 1.81, p=0.684).KEY WORDS: Risk factors, Stress fractures     

Short-term wound complications after application of flaps for coverage of traumatic soft-tissue defects about the tibia. The Lower Extremity Assessment Project (LEAP) Study Group

BACKGROUND: The purpose of the present study was to compare the rate of short-term wound complications associated with rotational flaps and that associated with free flaps for coverage of traumatic soft-tissue defects about the tibia. METHODS: Of 601 patients prospectively enrolled in a multicenter study of high-energy trauma of the lower extremity, 190 patients (195 limbs) required flap coverage and had six months of follow-up. The injury data included the ASIF/OTA classification of the tibial fracture and the soft-tissue injury and the functional status of the neurovascular and muscular structures of the soft-tissue compartments at the time of soft-tissue coverage. The treatment data consisted of the type of flap, the timing of the flap coverage, and the type of fixation. The patient characteristics that were recorded included the age, gender, presence of comorbidities, and smoking status at the time of the injury. Short-term complications included wound infection, wound necrosis, and loss of the flap within the first six months after the injury. RESULTS: Eighty-eight limbs were treated with a rotational flap, and 107 limbs were treated with a free flap. Overall, complications occurred after fifty-three (27 percent) of the 195 flap procedures; forty-six (87 percent) of the fifty-three required operative treatment. The two treatment groups were similar with respect to age, gender, comorbidities, preinjury smoking status, ASIF/OTA classification of the fracture, and prevalence of vascular injury requiring repair (p>0.05). There were two important differences between the two groups. First, three of the four leg compartments--that is, the anterior, lateral, and deep posterior compartments--were more likely to be functionally compromised in the free-flap group than in the rotational flap group (p<0.05), suggesting that patients in the free-flap group had sustained more severe soft-tissue injuries. Second, the Injury Severity Score was significantly higher (p = 0.001) in the rotational flap group (mean, 14 points) than in the free-flap group (mean, 11 points), suggesting that patients in the former group had sustained more substantial total body trauma. Overall, there were no significant differences between the two groups with respect to the complication rates. However, among those with the most severe grade of underlying osseous injury (an ASIF/OTA type-C injury), 44 percent of the limbs that were treated with a rotational flap had a wound complication compared with 23 percent of the limbs that were treated with a free flap (p = 0.10). To control for any differences between the two groups with respect to the severity of the injury, the treatment methods, or the patient characteristics, multivariate regression modeling was performed. An interaction effect between the type of flap and the severity of the underlying osseous injury demonstrated significance (p<0.05) after controlling for other factors. Of the limbs that sustained an ASIF/OTA type-C osseous injury, those that were treated with a rotational flap were 4.3 times more likely to have a wound complication requiring operative intervention than were those treated with a free flap. No significant difference in the rate of complications was detected with respect to the type of flap used for the limbs that had lower-grade osseous injuries. CONCLUSIONS: We found that use of a free flap to treat limbs with a severe underlying osseous injury was significantly less likely to lead to a wound complication requiring operative intervention than was use of a rotational flap.     

Assessing perceived need for mental health care in a community survey: development of the Perceived Need for Care Questionnaire (PNCQ)

  Background: The Perceived Need for Care Questionnaire (PNCQ) was designed for the Australian National Survey of Mental Health and Wellbeing. The PNCQ complemented collection of data on diagnosis and disability with the survey participants' perceptions of their needs for mental health care and the meeting of those needs. The four-stage design of the PNCQ mimics a conversational exploration of the topic of perceived needs. Five categories of perceived need are each assigned to one of four levels of perceived need (no need, unmet need, partially met need and met need). For unmet need and partially met need, information on barriers to care is collected. Methods: Inter-rater reliabilities of perceived needs assessed by the PNCQ were examined in a study of 145 anxiety clinic attenders. Construct validity of these items was tested, using a multi-trait multi-method approach and hypotheses regarding extreme groups, in a study with a sample of 51 general practice and community psychiatric service patients. Results: The instrument is brief to administer and has proved feasible for use in various settings. Inter-rater reliabilities for major categories, measured by the kappa statistic, exceeded 0.60 in most cases; for the summary category of all perceived needs, inter-rater reliability was 0.62. The multi-trait multi-method approach lent support to the construct validity of the instrument, as did findings in extreme groups. Conclusions: The PNCQ shows acceptable feasibility, reliability and validity, adding to the range of assessment tools available for epidemiological and health services research. Accepted: 5 June 2000     

Determinants of disability after lower extremity fracture

BACKGROUND: Factors influencing the progression of physical impairment to patient-perceived disability are not well known. We sought to better understand this relationship in the setting of injury. METHODS: We followed a cohort of 302 patients with lower extremity fractures over a 1-year period. Physical impairment was assessed by range of motion, strength, and pain. Range of motion and strength were assessed together as a proportion of normal function of the extremity (impairment score). Pain was assessed using a Visual Analogue Scale (VAS) pain score. Disability was assessed using the Sickness Impact Profile (SIP), a widely used measure of patient-perceived limitations of everyday activities attributable to illness. The SIP was administered during hospitalization to assess preinjury baseline. Impairment assessment and readministration of the SIP were performed at 12 months after injury. RESULTS: Impairment in leg function (range of motion and strength) was highly correlated (p < 0.001) with overall SIP score at 12 months, but accounted for only 23% of the variance in overall SIP scores. Likewise, VAS pain score was highly correlated (p < 0.001) with overall SIP score at 12 months, but accounted for only 29% of the variance in overall SIP scores. In a multivariate linear regression analysis, variables that were independently associated with overall SIP score included impairment score, VAS pain score, preinjury SIP, poverty status, education status, social support, having hired a lawyer, and involvement with workers' compensation. These variables accounted for 52% of the variance in overall SIP scores at 12 months. CONCLUSION: The degree of physical impairment accounts for only a small amount of the variance in disability from lower extremity fracture. Identifiable patient characteristics including age, socioeconomic status, preinjury health, and social support together with impairment account for over half of the variance in long-term disability. Further research is needed to increase understanding of other factors that influence the progression of impairment to disability, especially those factors that may be amenable to intervention.