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H Holmberg

Publications and source records attributed to H Holmberg.

At least 19 recordsLinked to original sources
PubMed2005

Classification of motor commands using a modified self-organising feature map.

In this paper, a control system for an advanced prosthesis is proposed and has been investigated in two different biological systems: (1) the spinal withdrawal reflex system of a rat and (2) voluntary movements in two human males: one normal subject and one subject with a traumatic hand amputation. The small-animal system was used as a model system to test different processing methods for the prosthetic control system. The best methods were then validated in the human set-up. The recorded EMGs were classified using different ANN algorithms, and it was found that a modified self-organising feature map (SOFM) composed of a combination of a Kohonen network and the conscience mechanism algorithm (KNC) was superior in performance to the reference networks (e.g. multi-layer perceptrons) as regards training time, low memory consumption, and simplicity in finding optimal training parameters and architecture. The KNC network classified both experimental set-ups with high accuracy, including five movements for the animal set-up and seven for the human set-up.

Adult↗
PubMed2003

Microbiological etiology in clinically diagnosed community-acquired pneumonia in primary care in Orebro, Sweden.

OBJECTIVE: To study the etiology of clinically diagnosed community-acquired pneumonia (CAP) in antibiotically naive patients attending a primary care center and treated at their homes. METHODS: A three-year prospective study was carried out, and 177 patients presenting with clinical signs of CAP were included. All patients had chest X-rays after inclusion, and 82 (46%) showed infiltrates. Nasopharyngeal swab culture was performed on all patients, and 51% produced a representative sputum sample. Paired sera were obtained from 176 patients. RESULTS: Among the 82 patients with radiographically proven CAP, Streptococcus pneumoniae was detected in 26 patients (32%), Haemophilus influenzae in 23 (28%), Mycoplasma pneumoniae in 15 (18%), and Chlamydia pneumoniae in four (5%). Serologic evidence of a viral infection was found in 13 patients (16%). Among the 95 patients without infiltrates, S. pneumoniae was found in 21 (22%), H. influenzae in 14 (15%), M. pneumoniae in two (2%), and C. pneumoniae in five (5%). Viral infection was detected in 19 (20%) of these 95 patients. CONCLUSION: In primary care in Sweden, the initial antibiotic treatment in any patient with pneumonia should be effective against S. pneumonia and H. influenzae. In addition, M. pneumoniae should be targeted during recurrent epidemics. C. pneumoniae, and especially Legionella, seem to be uncommon in primary care.

Community-Acquired Infections↗
PubMed2001

Clinical significance of nested polymerase chain reaction and immunofluorescence for detection of Pneumocystis carinii pneumonia.

OBJECTIVE: To study the clinical significance of a nested polymerase chain reaction (PCR) method compared to immunofluorescence (IF) for detection of Pneumocystis carinii. METHODS: The medical records of 89 patients with 91 episodes of pneumonia were scrutinised retrospectively. The pneumonia episodes were divided into categories according to the likelihood that the patient had had clinical Pneumocystis carinii pneumonia (PCP). All respiratory tract samples from the 89 patients (34 broncho-alveolar lavage (BAL) and 57 sputa) were tested for Pneumocystis carinii by IF and nested PCR. RESULTS: Fifteen episodes, as diagnosed by IF, were classified as true PCP (combination of the groups with definite and probable PCP; sensitivity 60%, specificity 97%). Among the P. carinii DNA-positive episodes, detected with nested PCR, 24 were classified as true PCP (combination of the groups with definite and probable PCP; sensitivity 96%, specificity 59%), since all IF-positive samples were nested PCR positive. Only one pneumonia episode classified as a probable PCP, was negative with both methods, as applied to a BAL sample. CONCLUSIONS: IF applied to BAL or sputum seems to be the most specific method for diagnosis of clinical PCP. Additional clinical cases can be found by nested PCR, although this then gives a high risk of detecting subclinical colonisation of P. carinii.

Adolescent↗
PubMed2000

Functional connections are established in the deafferented rat spinal cord by peripherally transplanted human embryonic sensory neurons.

Functionally useful repair of the mature spinal cord following injury requires axon growth and the re-establishment of specific synaptic connections. We have shown previously that axons from peripherally grafted human embryonic dorsal root ganglion cells grow for long distances in adult host rat dorsal roots, traverse the interface between the peripheral and central nervous system, and enter the spinal cord to arborize in the dorsal horn. Here we show that these transplants mediate synaptic activity in the host spinal cord. Dorsal root ganglia from human embryonic donors were transplanted in place of native adult rat ganglia. Two to three months after transplantation the recipient rats were examined anatomically and physiologically. Human fibres labelled with a human-specific axon marker were distributed in superficial as well as deep laminae of the recipient rat spinal cord. About 36% of the grafted neurons were double labelled following injections of the fluorescent tracers MiniRuby into the sciatic and Fluoro-Gold into the lower lumbar spinal cord, indicating that some of the grafted neurons had grown processes into the spinal cord as well as towards the denervated peripheral targets. Electrophysiological recordings demonstrated that the transplanted human dorsal roots conducted impulses that evoked postsynaptic activity in dorsal horn neurons and polysynaptic reflexes in ipsilateral ventral roots. The time course of the synaptic activation indicated that the human fibres were non-myelinated or thinly myelinated. Our findings show that growing human sensory nerve fibres which enter the adult deafferentated rat spinal cord become anatomically and physiologically integrated into functional spinal circuits.

Action Potentials↗
PubMed1999

Developmental tuning in a spinal nociceptive system: effects of neonatal spinalization.

Recent studies indicate a modular organization of the nociceptive withdrawal reflex system. Each module has a characteristic receptive field, closely matching the withdrawal movement caused by its effector muscle. In the rat, the strength of the sensory input to each module is tuned during the first postnatal weeks, i.e., erroneous spinal connections are depressed, and adequate connections are strengthened. To clarify if this tuning is dependent on supraspinal structures, the effect of a complete neonatal spinal cord transection on the postnatal tuning of withdrawal reflexes was studied. The nociceptive receptive fields of single hindlimb muscles and compound withdrawal reflexes were examined in decerebrate unanesthetized and awake rats, respectively. Noxious thermal CO(2) laser stimulation was used to evoke reflex responses. Neonatal spinal cord transection resulted in a disrupted reflex organization in the adult rat, resembling that previously found in neonatal rats. The receptive fields of single hindlimb muscles exhibited abnormal distribution of sensitivity not matching the withdrawal action of the effector muscles. Likewise, the composite nocifensive movements, as documented in the awake rat, often resulted in erroneous movements toward the stimulus. It is concluded that withdrawal reflexes do not become functionally adapted in rats spinalized at birth. These findings suggest a critical role for supraspinal systems in the postnatal tuning of spinal nociceptive systems.

Animals↗
PubMed1999

Perforated silicon nerve chips with doped registration electrodes: in vitro performance and in vivo operation.

An in vitro model was developed for the study of signal transduction between a Cu-wire, miming a neural signal source, and recording electrodes on perforated silicon chips. Phosphorous doped electrodes were used to achieve an all silicon device. The model was used to study signal amplitude as a function of the spatial position, and distance to the signal source. Recordings of the signal crosstalk to neighboring electrodes on the chips were made. It was found that the amplitude decreased by a factor of two at a distance of 50 microns between the electrode surface and the signal source. The chip electrode signal crosstalk was found to be 6 dB using an external reference electrode. Improvements were accomplished with an on chip reference electrode giving a crosstalk suppression of 20 dB. Impedance analysis showed that doped silicon electrodes displayed similar characteristics as Cu-electrodes at frequencies above 3 kHz. Sieve electrodes were implanted in the rat sciatic nerve and following a 10-week nerve regeneration period the dorsal and ventral (L5) roots in the spinal cord were stimulated. Compound action potentials were recorded via the chip. Stimulating the regenerated sciatic nerve via the sieve electrode also induced lower leg muscle contraction activity.

Action Potentials↗
PubMed1998

Evaluation of Alcaligenes eutrophus cells as an NADH regenerating catalyst in organic-aqueous two-phase system.

A soluble NAD-dependent hydrogenase contained in Alcaligenes eutrophus was evaluated as a coenzyme regenerating catalyst in an organic-aqueous two-phase (predominantly organic) system. The horse-liver alcohol-dehydrogenase (HLADH) catalyzed reduction of cyclohexanone to cyclohexanol was used as a model reaction. The impact of different solvents (selected to span a large variety of principal properties) on the stability and activity of the HLADH, using substrate-driven regeneration, was studied. Solvents suitable for the HLADH were then selected for an evaluation of the hydrogenase-driven coenzyme regeneration. Hydrophobic solvents such as heptane, toluene, and 1,1,1-trichloroethane were found to be suitable for the coupled reactions catalyzed by HLADH and hydrogenase. Nonimmobilized cells, permeabilized with cetyl-trimethyl-ammonium bromide, were the most efficient preparation for the regeneration of NADH. The use of this preparation in heptane (10% water) was optimized with respect to the yield obtained in the HLADH-catalyzed reduction of cyclohexanone. Using the optimized conditions, yields of 99% cyclohexanol were obtained.

Alcaligenes↗
PubMed1998

Economic evaluation of screening for prostate cancer: a randomized population based programme during a 10-year period in Sweden.

Prostate cancer is a growing health problem representing considerable costs. Screening and early curative treatment may reduce morbidity and possibly prevent future escalating costs. However, population screening programmes are generally not well accepted at present due to uncertainty about whether screening for prostate cancer can result in reduced mortality. Evidence from large, randomized, controlled trials is still lacking. The objective of this study was to calculate clinical and economic consequences of general prostate cancer screening based on a limited screening trial in a Swedish community and a decision-tree model. A random selection of 1492 men (50-69 years) were invited to repeated screening in 1987. They have been examined every third year (four rounds). The other 7679 men in the population act as controls. The results show that the total incremental health care costs for prostate cancer will increase by 179 million SEK per year with screening compared to no-screening. The number of detected cases of localized cancer will increase by about 1000, which represents an additional cost of about 158,000 SEK per case. In conclusion, general screening for prostate cancer can be performed with a reasonable cost per detected localized cancer. Information on the long-term effect on life quality and cancer mortality is unknown.

Aged↗
PubMed1998

Impact on health service costs of medical technologies used in management of prostatic cancer.

The aim of the study was to calculate the direct costs for the management of prostatic cancer throughout the need for care period. The impact of new medical technologies was analysed on the basis of an earlier cost study. The records of all 128 men in a defined population who died in 1992-93 and had been diagnosed with prostatic adenocarcinoma were retrospectively reviewed from diagnosis to death. The median cost per case, SEK 86,400, was significantly lower than the average cost per case, SEK 135,000, largely because of a few high-cost patients (in 20% of cases the cost exceeded SEK 250,000). Analysis of cost distribution throughout the need for care period showed that about 84% of the total cost per case was incurred during the the 3 years up to death. Estimated total direct care costs due to prostatic cancer in Sweden in the mid-1980s and early 1990s rose from approx. SEK 550 million to approx. SEK 780 million (1993 prices).

Adenocarcinoma↗
PubMed1998

Community-acquired pneumonia in adults.

Efforts to reduce hospitalization or the length of stay are common topics in papers published last year. Chlamydia pneumoniae is now recognized worldwide as a common pathogen in community-acquired pneumonia. A great variation in the frequency of various pathogens is found in different countries, stressing the importance of ascertaining the aetiological and epidemiological situation in each respective country.

Journal Article↗
PubMed1998

Antibody response in Staphylococcus aureus septicaemia--a prospective study.

Formation of serum antibodies against alpha-toxin, teichoic acid and lipase was followed in 63 patients with Staphylococcus aureus septicaemia in 240 consecutive serum samples. Control subjects comprised 23 patients with septicaemia due to other causes and 21 febrile patients without septicaemia. An antibody response against alpha-toxin, measured by ELISA, was most common (40%) in the initial serum, but antibody to teichoic acid was present in the highest number of positive patients (60%) when samples were drawn between 0 and 30 days: 74% of the patients showed a positive antibody response to at least one of the three antigens. When complicated versus uncomplicated septicaemia was compared (samples taken 8-14 days), 14 (45%) of 31 patients had a positive response against alpha-toxin versus 12 (75%) of 16, against teichoic acid 16 (51%) of 31 versus 12 (75%) of 16 and against lipase 15 (48%) of 31 versus 8 (50%) of 16. Patients with low initial antibody levels displayed a poorer antibody response than those with higher initial antibody levels. This phenomenon was observed with all three antigens, but was most pronounced with alpha-toxin. The initial antibody levels may predict the antibody response during the course of the disease. ELISA titres against alpha-toxin correlated (r=0.87) with biological neutralising activity of the antisera. The results may indicate a biological role of serum antibodies in staphylococcal septicaemia.

Adolescent↗
PubMed1998

Cytokine responses in patients with pneumonia caused by Chlamydia or Mycoplasma.

The serum concentrations of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) were measured by enzyme immunoassays in 44 patients with Chlamydia (n = 13) or Mycoplasma (n = 14) pneumonia or influenza A infection (n = 17) and in 20 control subjects. The levels of IFN-gamma were raised in 29/44 patients. The concentrations of IL-6 were raised in 32/44 patients. Raised levels of TNF-alpha were seen in 26/44 but there was no significant difference between the levels of the different groups of patients. All three cytokines indicated clinical recovery when acute and convalescent samples from 10 patients with Chlamydia pneumonia were analyzed. IFN-gamma, IL6 and TNF-alpha are present in the circulation in the majority of patients with Chlamydia and Mycoplasma pneumonia and in influenza A infection. We suggest that repeated measurement of cytokines, such as IL-6, IFN-gamma and TNF-alpha, may be useful in the management of lower respiratory tract infections but further studies are needed to define the value of cytokine measurements in acute pneumonia.

Adolescent↗
PubMed1998

Secretion of IL-6, IL-8 and G-CSF by human endothelial cells in vitro in response to Staphylococcus aureus and staphylococcal exotoxins.

The capacity of endothelial cells to produce and release cytokines (IL-6, IL-8 and G-CSF) in response to exposure to Staphylococcus aureus strains or staphylococcal exotoxins (alpha-toxin, enterotoxin A and TSST-1) was investigated. An endothelial cell culture model of human umbilical vein endothelial cells (HUVEC) was used. Five out of ten clinical isolates of S. aureus were found to induce cytokine production and release from endothelial cells. Four of the five isolates that induce cytokine release produced enterotoxin A, B, C, D and/or TSST-1, compared with two of those that did not induce release. Purified staphylococcal exotoxins (1 pg/ml-1 microg/ml) did not act as primary stimuli and induced no detectable cytokine secretion. When endothelial cells were prestimulated with IL-1beta or TNF alpha at a concentration of 1 ng/ml for 2 h, IL-1beta served as a potent primary stimulus for IL-6, IL-8 and G-CSF production, whereas TNF alpha did not induce any significant cytokine release during the subsequent 24 h. A further increase in IL-6 and G-CSF release, but not of IL-8, was observed when IL-1beta prestimulated cells were exposed to alpha-toxin or TSST-1. However, to potentiate cytokine production (IL-6 and IL-8) by SEA, both IL-1beta and the toxin had to be present simultaneously. Our data show that S. aureus, but not staphylococcal exotoxins, have the capacity to act as primary stimuli of endothelial cells and induce production and release of cytokines. IL-1beta may prime HUVEC to release IL-6, IL-8 and G-CSF prior to subsequent stimulation with staphylococcal exotoxins.

Bacterial Toxins↗
PubMed1997

Developmental adaptation of rat nociceptive withdrawal reflexes after neonatal tendon transfer.

Nociceptive withdrawal reflexes (NWRs) were studied in adult rats in which the movement patterns produced by single muscles had been altered by neonatal tendon transfer. NWRs evoked by cutaneous noxious mechanical and thermal (CO2-laser) stimulation were recorded using electromyography in a decerebrate spinal preparation. The sensitivity distribution within the receptive fields of the NWRs of the extensor digitorum longus and the peronei muscles exhibited changes corresponding to the altered movement patterns. No detectable change of NWRs was found in normal muscles whose receptive fields overlapped that of the modified muscle. Furthermore, NWRs of muscles that regained an essentially normal function after neonatal tendon transfer did not differ from normal. It is proposed that a developmental experience-dependent mechanism, which takes into account the hindlimb movement pattern caused by contraction of single muscles, underlies the functionally adapted organization of adult NWRs.

Adaptation, Physiological↗
PubMed1997

Bottle-blowing in hospital-treated patients with community-acquired pneumonia.

A study was carried out to determine whether bottle-blowing has any positive effects in patients with pneumonia. In a prospective open study 145 adults with untreated community-acquired pneumonia requiring hospitalization were randomized to early mobilization (group A), to sit up and take 20 deep breaths on 10 occasions daily (group B), or to sit up and to blow bubbles in a bottle containing 10 cm water through a plastic tube 20 times on 10 occasions daily (group C). Peak expiratory flow (PEF), vital capacity (VC), forced expiratory volume in 1 sec (FEV1) and serum concentration of C-reactive protein (CRP) were determined on admission, and on days 4 and 42. Fever duration and hospital stay were recorded. In a subset of 16 patients, single breath diffusion capacity of carbon monoxide was measured on 3 occasions. The patients in group A were hospitalized for a mean of 5.3 days, group B for 4.6 days and group C for 3.9 days. Treatment was a significant factor (p = 0.037) in a Cox regression model, with group C significantly better than group A (p = 0.01). The number of days with fever was 2.3, 1.7 and 1.6 in groups A, B and C respectively. These differences were not significant (p = 0.28). No significant differences were found between the groups regarding CRP, PEF, VC, FEV1, or diffusion capacity. Intensive bottle-blowing shortens the hospital stay in patients with pneumonia. The underlying mechanism is not clear.

Adolescent↗
PubMed1996

Developmental adaptation of withdrawal reflexes to early alteration of peripheral innervation in the rat.

1. In adult decerebrate spinal rats whose plantar nerves (PLN) had been transected at either postnatal day 1 (P1) or P21 the nociceptive withdrawal reflexes (NWR) of musculi extensor digitorum longus (EDL), peroneus longus (PER) and semitendinosus (ST) were characterized with respect to receptive field (RF) organization, magnitude and time course, using electromyography. Thermal (short CO2 laser pulses) and mechanical (calibrated pinch) stimulation were used. The innervation patterns in normal and lesioned adult rats were assessed by acute nerve lesions. 2. The spatial organization of the mean mechano- and thermonociceptive RFs of all the muscles studied was similar to normal in both P1- and P21-lesioned rats, although in some P21-lesioned rats atypical EDL RFs were encountered. 3. In P1-lesioned rats thermo-NWR of PER and EDL had normal magnitudes, while mechano-NWR were reduced. In P21-lesioned rats both thermo- and mechano-NWR of these muscles had reduced magnitudes. Except for thermo-NWR of ST in P1-lesioned rats, which were increased, NWR of ST had normal magnitudes in both P1- and P21-lesioned rats. The time course of thermonociceptive NWR of the muscles studied were near normal in both P1- and P21-lesioned rats. 4. Acute nerve lesions in adult P1-lesioned rats revealed an essentially abolished contribution to NWR from the PLN. Instead, the contribution to NWR from other hindpaw nerves, such as the superficial and deep peroneal nerves, was dramatically increased. By contrast, in P21-lesioned rats, the regenerated PLN contributed significantly to the NWR. 5. It is concluded that despite profound alterations of plantar hindpaw innervation induced by early PLN transection the cutaneous nociceptive input to NWR attained an essentially normal spatial organization. An experience-dependent mechanism is suggested to be instrumental in adapting the reflex connectivity to the peripheral innervation.

Adaptation, Physiological↗