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Biomedical subjects

Z Durrani

Publications and source records attributed to Z Durrani.

At least 19 recordsLinked to original sources
PubMed2001

Analysis of host responses of guinea pigs during Helicobacter pylori infection.

Host responses of guinea pigs infected with Helicobacter pylori were investigated. Passaged H. pylori colonised the stomach for up to 13 weeks after infection, but after 1 month the number of bacteria fell sharply. Specific antibodies, predominantly of the IgG2 subtype, were present from week 3 onwards. Antibodies to urease A and flagella were abundant. Severe inflammation of the gastric mucosa and damage to the stomach epithelium was seen. Infiltrates of mononuclear cells and eosinophils were found near the parietal glands. As infection progressed, inflammation and tissue damage became more localised and more variable between individual animals. These parameters can be used as markers for colonisation of the stomach by H. pylori.

Animals↗
PubMed2000

Immunogenic and antigenic dominance of a nonneutralizing epitope over a highly conserved neutralizing epitope in the gp41 envelope glycoprotein of human immunodeficiency virus type 1: its deletion leads to a strong neutralizing response.

The Kennedy peptide, (731)PRGPDRPEGIEEEGGERDRDRS(752), from the cytoplasmic domain of the gp41 transmembrane envelope glycoprotein of HIV-1 contains a conformationally dependent neutralizing epitope (ERDRD) and a linear nonneutralizing epitope (IEEE). No recognized murine T cell epitope is present. The peptide usually stimulates virus-specific antibody, but this is not always neutralizing. Here we show that IEEE (or possibly IEEE plus adjacent sequence) is immunogenically and antigenically dominant over the ERDRD neutralizing epitope. Thus rabbits immunized in a variety of routes, doses, and adjuvants with a chimeric cowpea mosaic virus (CPMV) expressing the Kennedy peptide on its surface (CPMV-HIV/1) synthesized IEEE-specific serum antibody but no ERDRD-specific or HIV-1-neutralizing antibody. To test if this resulted from immunodominance or from a hole in the antibody repertoire, we immunized rabbits with chimera CPMV-HIV/29, which expresses the GERDRDR part of the Kennedy sequence. This chimera readily stimulated ERDRD-specific, neutralizing antibody. In mice the situation was less extreme, but individual animals with low neutralizing titers had a high ratio of IEEE-specific:ERDRD-specific antibody. Data are consistent with immunodominance of IEEE over ERDRD in the Kennedy peptide. IEEE-specific antibody was also antigenically dominant and prevented ERDRD-specific antibody from binding to its epitope and from neutralizing HIV-1. It may be that HIV-1 has evolved a nonneutralizing immunodominant epitope that allows it to possess a neutralizing epitope without suffering the consequences, and this idea is supported by the covariance of both epitope sequences. To our knowledge this is the first example of a defined sequence that controls the activity of an adjacent epitope.

Amino Acid Sequence↗
PubMed1999

Non-pertussis components of combination vaccines: problems with potency testing.

Vaccines comprising combinations of diphtheria, tetanus and pertussis (DTP) with Haemophilus influenzae type b polysaccharide-protein conjugate (Hib), inactivated poliomyelitis virus (IPV) and hepatitis B virus (HBV) are already available, and new combinations using acellular pertussis components in a triple vaccine (DTaP) are under development. Evidence to date has shown that control of the efficacy, safety and stability of combination vaccines cannot be based on information already available on the individual components or existing licensed formulations. Several examples of immunological interference between components of a combination vaccine have been observed both in clinical trials and in laboratory tests. Examples of these for D, T and Hib components in DTP and DTaP combinations have been investigated.

Animals↗
PubMed1999

Analysis of vacA, cagA, and IS605 genotypes and those determined by PCR amplification of DNA between repetitive sequences of Helicobacter pylori strains isolated from patients with nonulcer dyspepsia or mucosa-associated lymphoid tissue lymphoma.

The vacA s and m genotypes and the presence of cagA and IS605 were determined in Helicobacter pylori strains from patients with mono- and multiple infections. Surprisingly, these genetic markers were not associated with nonulcer dyspepsia or mucosa-associated lymphoid tissue lymphoma. The presence of cagA correlated with the presence of the vacA s1 allele (P < 0.05), whereas the presence of IS605 was associated with the presence of the s2 allele (P < 0.05).

Antigens, Bacterial↗
PubMed1998

Intranasal immunization with a plant virus expressing a peptide from HIV-1 gp41 stimulates better mucosal and systemic HIV-1-specific IgA and IgG than oral immunization.

Control of pandemic human immunodeficiency virus type 1 (HIV-1) infection ideally requires specific mucosal immunity to protect the genital regions through which transmission more often occurs. Thus a vaccine that stimulates a disseminated mucosal and systemic protective immune response would be extremely useful. Here we have investigated the ability of a chimeric plant virus, cowpea mosaic virus (CPMV), expressing a 22 amino acid peptide (residues 731-752) of the transmembrane gp41 protein of HIV-1 IIIB (CPMV-HIV/1), to stimulate HIV-1-specific and CPMV-specific mucosal and serum antibody following intranasal or oral immunization together with the widely used mucosal adjuvant, cholera toxin. CPMV-HIV/1 has been shown previously to stimulate HIV-1-specific serum antibody in mice by parenteral immunization. All mice immunized intranasally with two doses of 10 microg of CPMV-HIV/1 produced both HIV-1-specific IgA in faeces as well as higher levels of specific, predominantly IgG2a, serum antibody. Thus there was a predominantly T helper 1 cell response. All mice also responded strongly to CPMV epitopes. Oral immunization of the chimeric cowpea mosaic virus was less effective, even at doses of 500 microg or greater, and stimulated HIV-1-specific serum antibody in only a minority of mice, and no faecal HIV-1 specific IgA.

AIDS Vaccines↗
PubMed1996

Stimulation of neutralizing antibodies to human immunodeficiency virus type 1 in three strains of mice immunized with a 22 amino acid peptide of gp41 expressed on the surface of a plant virus.

A plant virus, cowpea mosaic virus, expressing a 22 amino acid peptide 731-752 of the gp41 glycoprotein of human immunodeficency virus type 1 (HIV-1 IIIB), was shown previously to stimulate HIV-1 cross reactive neutralizing antibodies in adult C57/BL6 mice. Here some parameters concerning the stimulation of HIV-1-specific neutralizing and ELISA antibody have been determined in adult C57/BL6, C3H/He-mg and BALB/c mice. Two injections per mouse of all CPMV-HIV/1 doses tested (100, 10 and 1 microgram chimera which contained, respectively, 1700, 170 and 17 ng HIV peptide per injection) stimulated a strong serum neutralizing antibody response in all mice. One hundred micrograms or 10 micrograms CPMV-HIV/1 per injection gave 99% neutralization of HIV-1 IIIB in C8166 cells at a serum dilution of 1/200, whereas sera from mice immunized with 1 microgram per injection neutralized virus to 97%, 79% and 63% at a 1/200 dilution of serum from C3H/He-mg, C57/BL6 and BALB/c mice, respectively. Restimulation of these mice with the same immunogen dose marginally increased the neutralization titres. The longevity of the neutralizing antibody response increased as the immunogen dose decreased, and was dependent on the strain of mouse, in the order C57/BL6C3H/He-mg BALB/c. Re-immunization with a third injection improved the longevity of the antibody response. All mice immunized with 100 micrograms CPMV-HIV/1 responded with ELISA antibody to the gp41 peptide bound in solid phase. Ten micrograms stimulated ELISA antibody in some but not all mice, while mice immunized with 1 microgram had no detectable ELISA antibody. This synthesis of ELISA antibody decreased > or = 230-fold over the range of immunogen doses tested but, in the same mice, the neutralizing antibody response decreased only twofold, showing an unusual bias to production of the latter. Neutralizing antibodies were thus stimulated at a lower immunogen dose than ELISA antibodies. Antibody which was affinity purified using the free gp41 peptide gave a good ELISA titre but did not neutralize HIV-1, suggesting that the neutralizing antibody is recognizing a conformational epitope on the gp41 oligomer.

Amino Acid Sequence↗
PubMed1995

Human immunodeficiency virus type 1-neutralizing antibodies raised to a glycoprotein 41 peptide expressed on the surface of a plant virus.

An oligonucleotide encoding the amino acids 731-752 of the gp41 envelope protein of the human immunodeficiency virus type 1 strain IIIB, which is known to induce cross-reactive neutralizing antibodies in humans, was inserted into a full-length clone of the RNA encoding the coat proteins of cowpea mosaic virus (RNA 2 of CPMV). When transfected together with RNA 1 of CPMV, transcribed RNA 2 was able to replicate in plants and form infectious virions (CPMV-HIV). Purified virions were injected subcutaneously with alum adjuvant into adult C57/BL6 mice to determine their ability to stimulate ELISA and neutralizing antibody specific for HIV-1. Antisera to CPMV-HIV obtained after only two injections gave a strong ELISA response (mean of 1:25,800) using the free gp41 peptide as antigen, showing that the gp41 peptide incorporated into the chimera was immunogenic. The same antisera gave 97% neutralization of HIV-1 IIIB at 1:100 dilution, with a highly uniform response in all (six of six) animals tested. A third injection barely increased the neutralization titer. Normal mouse serum had no neutralizing activity. Antisera also strongly neutralized the HIV-1 strains RF and SF2. ELISA and neutralizing activity to HIV-1 IIIB declined after the second injection and were undetectable after 7 weeks, but were restimulated to the same level after the third injection. Neutralization was marginally more stable after the third injection. Antibody specific for CPMV epitopes was equally short lived. A bonus of this system was unexpected neutralizing activity specifically stimulated by unmodified CPMV virions, although this amounted to no more than 10% of the neutralizing activity stimulated by the CPMV-HIV chimera.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Piriformis muscle syndrome: an underdiagnosed cause of sciatica.

This is a retrospective review of 26 patients with sciatica due to the piriformis muscle syndrome. Most patients had pain in the buttock area and sciatica, and most experienced difficulty walking and sitting, even for short periods of time. Reproduction of the sciatica upon deep palpation, either by gluteal or rectal route, was diagnostic. Reproduction of sciatica occurred in 92% of the patients upon deep digital palpation and in 100% of the patients upon rectal or pelvic examination. Other signs were helpful but not consistent. After the appropriate diagnosis, the treatment was relatively easy and rewarding. This study emphasizes that the diagnosis of piriformis muscle syndrome is clinical; without the appropriate clinical examination, it can be easily misdiagnosed.

Adult↗
PubMed1990

Brachial plexus block with a new local anaesthetic: 0.5 per cent ropivacaine.

A new local anaesthetic, ropivacaine hydrochloride, was used in a concentration of 0.5 per cent in 32 patients receiving a subclavian perivascular block for upper extremity surgery. One group (n = 15) received 0.5 per cent ropivacaine without epinephrine and a second group (n = 17) received 0.5 per cent ropivacaine with epinephrine in a concentration of 1:200,000. Anaesthesia was achieved in 87 per cent of the patients in both groups in all of the C5 through T1 brachial plexus dermatomes. Motor block was profound with 100 per cent of patients in both groups developing paresis at both the shoulder and hand and 100 per cent developing paralysis at the shoulder. There was a rapid initial onset of sensory block (a mean of less than four minutes for analgesia) with a prolonged duration (a mean of greater than 13 hr of analgesia). The addition of epinephrine did not significantly affect the quality or onset of sensory or motor block. The duration of sensory block was reduced by epinephrine at T1 for analgesia and at C7, C8, and T1 for anaesthesia. The duration of sensory block in the remaining brachial plexus dermatomes as well as the duration of motor block was not effected by epinephrine. There was no evidence of cardiovascular or central nervous system toxicity in either group with a mean dose of 2.5-2.6 mg.kg-1 ropivacaine.

Adult↗
PubMed1989

Ketamine for intravenous regional anesthesia.

We studied ketamine intravenous regional anesthesia of the upper extremity in volunteers using concentrations of 0.5%, 0.3%, and 0.2%. Ketamine 0.5 and 0.3% produced adequate intravenous regional anesthesia. Anesthesia was inadequate when a 0.2% concentration was used. However, although the 0.3% concentration provides complete sympathetic, sensory, and motor blockade when injected into the isolated extremity, unpleasant psychotomimetic effects after the release of the tourniquet limit the usefulness of this use of ketamine. Ketamine cannot be recommended for intravenous regional anesthesia unless these unpleasant side effects are abolished or controlled by means of pharmacologic adjuvants.

Adult↗
PubMed1987

Endocrine and hemodynamic effects of antagonism of fentanyl-induced respiratory depression by nalbuphine.

Endocrine and hemodynamic changes associated with the antagonism of fentanyl by nalbuphine have not been reported. Therefore, the authors studied ten patients after anesthetic induction with thiopental, fentanyl, tracheal intubation aided by succinylcholine and maintenance with diazepam, pancuronium, N2O, and further doses of fentanyl. Eight of the patients underwent cholecystectomy, one had a hysterectomy, and another had an abdominoplasty. After reversal of neuromuscular block at the conclusion of surgery, normal ventilation was restored by 0.22 +/- 0.02 mg/kg intravenous nalbuphine (mean +/- SEM). Plasma levels of free norepinephrine, histamine, and cortisol did not increase after antagonism of the fentanyl-induced respiratory depression, but plasma concentration of epinephrine increased significantly but without significant hemodynamic changes. Minute ventilation was 1.5 +/- 0.4 L/min before and 11 +/- 1, 10 +/- 1, 11 +/- 1, and 10 +/- 1 L/min at 15, 30, 45, and 60 min after antagonism; corresponding PaCO2 levels were 56 +/- 2, 44 +/- 1, 49 +/- 7, 49 +/- 1, 42 +/- 1 mm Hg. The mean analogue pain score remained below 1.5. We conclude that nalbuphine effectively antagonizes fentanyl-induced respiratory depression without adverse endocrine and circulatory changes or loss of analgesia.

Adult↗
PubMedDate not supplied

Interscalene cervical plexus block: a single-injection technic.

A review of the anatomy of the cervical plexus and surrounding structures suggests a single-injection technic which simplifies anesthesia of the cervical plexus and increases the margin of safety in this procedure. Used by the authors, the technic has been successful in 97 percent of over 100 cases.

Anesthesia, Conduction↗