Suppurative corneal ulceration in Bangladesh

Suppurative keratitis is an important preventable cause of blindness, particularly in the developing world. This study analyses 142 cases of suppurative keratitis referred to Chittagong Eye Infirmary, Bangladesh. Some 53.5% of cases were bacterial and 35.9% were fungal. The five most common pathogens were: Pseudomonas sp. 24%, Streptococcus pneumoniae 17%, Aspergillus sp. 13%, Fusarium sp. 7% and Curvularia sp. 6%. Gram stain and culture results were consistent in 62.6% of cases. Previous antibiotic treatment was a significant factor for failure of culture isolation and less so for Gram stain failure. On Gram stain, 55.9% of pseudomonal cases were missed, but only 2% of fungal cases were missed. Over all, Gram stain had a sensitivity of 62% and positive predictive value of 84% for bacterial cases, and 98% and 94% for fungal cases, respectively. Fungal ulcers were typically filamentous, but an antecedent history of trauma was not common. The most frequent injury was due to rice grains, but the inoculum appeared to be introduced during eye washing with contaminated water. Pseudomonal ulcers occurred most frequently in the monsoon season, and Fusarium cases were seen only in the hot, dry season.     

Psychiatric mental health nursing: challenge and change

. We invited Dr Peplau to provide a personal reflection on the recent history of psychiatric nursing and her thoughts on immediate challenges facing the profession. The paper is an individual scholar's commentary on the way that psychiatry has waxed and waned over the years, in relation to nursing. This historical review discovers and reports a challenge to current practice. Dr Peplau describes a professional shift that is pulling nurses toward the subordinate role observed earlier this century. The paper draws attention to how contemporary practice can be positively influenced, e.g., by giving a structure to the allocation and conduct of nurse–patient time.     

A novel 37-Kd adhesive membrane protein from cloned murine bone marrow stromal cells and cloned murine hematopoietic progenitor cells

The adhesion of hematopoietic progenitor cells to bone marrow stromal cells is critical to hematopoiesis and involves multiple effector molecules. Stromal cell molecules that participate in this interaction were sought by analyzing the detergent-soluble membrane proteins of GBI/6 stromal cells that could be adsorbed by intact FDCP-1 progenitor cells. A single-chain protein from GBI/6 cells having an apparent molecular weight of 37 Kd was selectively adsorbed by FDCP-1 cells. This protein, designated p37, could be surface-radiolabeled and thus appeared to be exposed on the cell membrane. An apparently identical 37- Kd protein was expressed by three stromal cell lines, by Swiss 3T3 fibroblastic cells, and by FDCP-1 and FDCP-2 progenitor cells. p37 was selectively adsorbed from membrane lysates by a variety of murine hematopoietic cells, including erythrocytes, but not by human erythrocytes. Binding of p37 to cells was calcium-dependent, and was not affected by inhibitors of the hematopoietic homing receptor or the cell-binding or heparin-binding functions of fibronectin. It is proposed that p37 may be a novel adhesive molecule expressed on the surface of a variety of hematopoietic cells that could participate in both homotypic and heterotypic interactions of stromal and progenitor cells.     

Nociceptive input to spinal interneurones in reflex pathways from group II muscle afferents in cats

Effects of noxious stimulation of the skin by radiant heat were tested on responses of first order interneurones in reflex pathways from group II muscle afferents in mid-lumbar, lower-lumbar and sacral segments of the spinal cord. In mid- and lower-lumbar segments both background discharges and monosynaptically evoked responses of intermediate zone interneurones were facilitated. Those of mid-lumbar dorsal horn interneurones were also facilitated suggesting that both these interneuronal populations contribute to the facilitation of flexion reflexes by nociceptors. In contrast, the dominating effects of noxious heat on sacral dorsal horn group II interneurones were inhibitory. The effects evoked by selective activation of C fibres, after A-delta fibres had been blocked by TTX, were similar to those obtained before TTX application.     

Only minor spinal motor reflex effects from feline group IV muscle nociceptors

The contribution of group III and IV muscle nociceptors activated by injection of KCl or bradykinin into the muscle artery (i.a.) of the gastrocnemius-soleus muscle to spinal motor reflex pathways was investigated in high spinal cats. Group I-III fibres were completely blocked by TTX, leaving group IV-fibre conduction intact. Thus, effects from i.a. KCl or bradykinin injection persisting after TTX were attributed to TTX resistant group IV fibres while the contribution of group III fibres was approximately defined by the difference between those effects and the control effects before TTX. Confirming former findings the chemical activation of group III and IV muscle afferents induced distinct reflex facilitation of the flexor posterior biceps semitendinosus and inhibition of the extensor quadriceps. After the block of all myelinated fibres by TTX the same stimuli induced only minor reflex effects mediated by the persistently conducting TTX resistant group IV afferents. It is concluded that the main functional meaning of group IV muscle afferents, which respond preferentially with a higher threshold to mechanical stimuli, is probably less related to reflex motor control than that of group III afferents.     

Cutaneous facilitation of transmission in reflex pathways from Ib afferents to motoneurones.

1. The effect of volleys in low threshold cutaneous afferents upon transmission of synaptic action from Ib afferents to motoneurones has been investigated with intracellular recording from alpha motoneurones to hind limb muscles. 2. There was facilitation from cutaneous afferents of transmission in excitatory and inhibitory reflex pathways from Ib afferents without any evidence for difference in effect on di- and trisynaptic pathways. It is postulated that volleys in cutaneous afferents evoke excitatory action in interneurones of these reflex pathways. 3. The time course of the facilitation suggest that cutaneous afferents have disynaptic excitatory connexions with the interneurones intercalated in the disynaptic Ib inhibitory pathways to motoneurones. 4. Some observations are reported suggesting that interneuronal transmission in Ib inhibitory pathways to motoneurones might be facilitated from Ia afferents. 5. The findings are discussed in relation to the presumed role of Ib reflex action in regulating muscle tension.     

Reflex pathways from group II muscle afferents

Summary A hypothesis is forwarded regarding the role of secondary spindle afferents and the FRA (flexor reflex afferents) in motor control. The hypothesis is based on evidence (cf. Lundberg et al. 1987a, b) summarized in 9 introductory paragraphs. Group II excitation. It is postulated that subsets of excitatory group II interneurones (transmitting disynaptic group II excitation to motoneurones) may be used by the brain to mediate motor commands. It is assumed that the brain selects subsets of interneurones with convergence of secondary afferents from muscles whose activity is required for the movement. During movements depending on coactivation of static -motoneurones impulses in secondary afferents may servo-control transmission to -motoneurones at an interneuronal level. The large group II unitary EPSPs in interneurones are taken to indicate that, given an adequate interneuronal excitability, impulses in single secondary afferents may fire the interneurone and produce EPSPs in motoneurones; interneuronal transmission would then be equivalent to that in a monosynaptic pathway but with impulses from different muscles combining into one line. It is postulated that impulses in the FRA are evoked by the active movements and that the role of the multisensory convergence from the FRA onto the group II interneurones is to provide the high background excitability which allows the secondary spindle afferents to operate as outlined above. The working hypothesis is put forward that a movement governed by the excitatory group II interneurones is initiated by descending activation of these interneurones, but is maintained in a later phase by the combined effect of FRA activity evoked by the movement and by spindle secondaries activated by descending activation of static -motoneurones. As in the original follow up length servo hypothesis (Rossi 1927; Merton 1953), we assume that a movement at least in a certain phase can be governed from the brain solely or mainly via static -motoneurones. However, our hypothesis implies that the excitatory group II reflex connexions have a strength which does not allow transmission to motoneurones at rest and that the increase in the gain of transmission during an active movement is supplied by the movement itself. Group II inhibition. It is suggested that the inhibitory reflex pathways like the excitatory ones have subsets of interneurones with limited group II convergence. When higher centres utilize a subset of excitatory group II interneurones to evoke a given movement, they may mobilize inhibitory subsets to inhibit muscles not required in the movement. Inhibition may be reciprocal of extensors during flexor activation (the spinal pattern), of flexors during extensor activation or of flexors and extensors in more complex movements involving cocontraction of other flexors and extensors. It is postulated that group II inhibition depends on conjoint activation from spindle afferents and other sources (descending and/or the FRA) so that inhibition may be coupled to group II excitation of other motoneurones. Such a coupling would correspond to the --linkage in reciprocal Ia inhibition (Lundberg 1970) and is denoted --linkage in lateral group II inhibition. FRA and other reflex pathways. Results are summarized showing that the FRA evoke convergent excitation in interneurones not only in group II reflex pathways but also in other reflex pathways like the reciprocal Ia inhibitory, the nonreciprocal group I inhibitory and probably also in specialized reflex pathways from cutaneous afferents. It is inferred that facilitation of reflex transmission by impulses in the FRA evoked by the active movement may be a general principle. In this way reflex transmission to -motoneurones may be weak at rest and not disturb passive movements but have a high gain when the reflexes are required to regulate active movement.This work was supported by the Swedish Medical Research Council (project no. 94)